The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3-D SYS CORP DEL COM NEW COM 88554D205 665 81,571 SH   SOLE   81,571 0 0
3M COMPANY COM 88579y101 1,098 6,680 SH   SOLE   6,680 0 0
A. O. SMITH CORPORATION COM 831865209 493 10,335 SH   SOLE   10,335 0 0
AAC HOLDINGS INC COM 000307108 129 193,025 SH   SOLE   193,025 0 0
ABBOTT LABORATORIES COM 002824100 1,189 14,213 SH   SOLE   14,213 0 0
ABBVIE INC SHS COM 00287y109 755 9,972 SH   SOLE   9,972 0 0
ACCENTURE PLC F CLASS A COM g1151c101 340 1,770 SH   SOLE   1,770 0 0
AIR PRODUCTS & CHEMICALS, INC. COM 009158106 479 2,158 SH   SOLE   2,158 0 0
ALLEGION PLC COM G0176J109 2,010 19,389 SH   SOLE   19,389 0 0
ALLSTATE CORPORATION COM 020002101 2,331 21,449 SH   SOLE   21,449 0 0
ALPHABET INC CLASS C COM 02079K107 127,507 104,600 SH   SOLE   104,600 0 0
ALPHABET INC. CLASS A COM 02079k305 1,423 1,165 SH   SOLE   1,165 0 0
AMAZON.COM INC COM 023135106 112,700 64,923 SH   SOLE   64,923 0 0
AMERICAN TOWER CORP COM 03027X100 133,389 603,216 SH   SOLE   603,216 0 0
AMGEN INC COM PV $0.0001 COM 031162100 969 5,006 SH   SOLE   5,006 0 0
ANSYS INC COM 03662Q105 217,331 981,799 SH   SOLE   981,799 0 0
APPLE INC COM 037833100 6,568 29,326 SH   SOLE   29,326 0 0
AT&T INC COM 00206r102 204 5,382 SH   SOLE   5,382 0 0
AUTOMATIC DATA PROC COM 053015103 2,157 13,361 SH   SOLE   13,361 0 0
BANK AMER CORP COM COM 060505104 363 12,461 SH   SOLE   12,461 0 0
BANK OF HAWAII CORP COM 062540109 253 2,942 SH   SOLE   2,942 0 0
BB&T CORPORATION COM 054937107 624 11,700 SH   SOLE   11,700 0 0
BEACON ROOFING SUPPLY INC COM 073685109 3,058 91,203 SH   SOLE   91,203 0 0
BECTON DICKINSON&CO COM 075887109 399 1,578 SH   SOLE   1,578 0 0
BERKLEY W R CORP COM 084423102 1,678 23,236 SH   SOLE   23,236 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 2,806 9 SH   SOLE   9 0 0
BERKSHIRE HATHAWAY INC CL B COM 084670702 7,954 38,237 SH   SOLE   38,237 0 0
BIO-TECHNE CORP COM 09073M104 147,570 754,179 SH   SOLE   754,179 0 0
BLACK KNIGHT INC COM 09215C105 91,155 1,492,871 SH   SOLE   1,492,871 0 0
BLACKLINE INC COM 09239B109 167,635 3,506,270 SH   SOLE   3,506,270 0 0
BRIGHT HORIZONS FAM SOL IN DEL COM 109194100 8,596 56,367 SH   SOLE   56,367 0 0
BROOKS AUTOMATION INC COM 114340102 134,498 3,632,133 SH   SOLE   3,632,133 0 0
CABLE ONE INC COM COM 12685J105 28,651 22,835 SH   SOLE   22,835 0 0
CALAVO GROWERS INC COM 128246105 5,814 61,081 SH   SOLE   61,081 0 0
CANADIAN NATL RY CO COM COM 136375102 1,797 20,000 SH   SOLE   20,000 0 0
CANTEL MEDICAL CORP COM 138098108 5,065 67,708 SH   SOLE   67,708 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 2,465 27,090 SH   SOLE   27,090 0 0
CARMAX INC COM 143130102 134,607 1,529,625 SH   SOLE   1,529,625 0 0
CBRE GROUP INC COM 12504L109 114,093 2,152,301 SH   SOLE   2,152,301 0 0
CELGENE CORP COM 151020104 276 2,775 SH   SOLE   2,775 0 0
CHEVRON CORP COM 166764100 648 5,462 SH   SOLE   5,462 0 0
CHUBB LTD COM h1467j104 654 4,050 SH   SOLE   4,050 0 0
CIGNA CORP COM 125523100 328 2,163 SH   SOLE   2,163 0 0
CISCO SYSTEMS INC COM COM 17275r102 3,102 62,787 SH   SOLE   62,787 0 0
COCA COLA COM COM 191216100 2,157 39,613 SH   SOLE   39,613 0 0
COGENT COMMUNICATIONS COM 19239V302 8,708 158,031 SH   SOLE   158,031 0 0
COLGATE-PALMOLIVE CO COM 194162103 867 11,800 SH   SOLE   11,800 0 0
COMCAST CORP NEW CL A COM 20030n101 6,160 136,657 SH   SOLE   136,657 0 0
CONCHO RES INC COM COM 20605P101 1,780 26,215 SH   SOLE   26,215 0 0
CONOCOPHILLIPS COM 20825c104 514 9,020 SH   SOLE   9,020 0 0
CONSOLIDATED EDISON INC COM COM 209115104 382 4,044 SH   SOLE   4,044 0 0
CONSTELLATION SOFTWARE INC. COM 21037x100 8,112 8,097 SH   SOLE   8,097 0 0
CORE LAB N.V. COM N22717107 1,007 21,607 SH   SOLE   21,607 0 0
COSTAR GROUP INC COM 22160N109 142,227 239,763 SH   SOLE   239,763 0 0
COUPA SOFTWARE COM 22266l106 3,165 24,426 SH   SOLE   24,426 0 0
CROWN CASTLE REIT INC COM 22822v101 8,016 57,666 SH   SOLE   57,666 0 0
CVS HEALTH CORP COM 126650100 228 3,622 SH   SOLE   3,622 0 0
DANAHER CORP COM 235851102 103,949 719,722 SH   SOLE   719,722 0 0
DELTA AIR LINES INC COM 247361702 230 4,000 SH   SOLE   4,000 0 0
DEXCOM INC COM 252131107 6,280 42,077 SH   SOLE   42,077 0 0
DISCOVER FINANCIAL SERVICES COM 254709108 5,293 65,269 SH   SOLE   65,269 0 0
DISNEY (WALT) CO COM STK COM 254687106 666 5,107 SH   SOLE   5,107 0 0
DOLLAR GENERAL COM 256677105 7,309 45,984 SH   SOLE   45,984 0 0
DOUGLAS DYNAMICS INC COM 25960R105 11,146 250,085 SH   SOLE   250,085 0 0
DUKE REALTY CORP REIT COM 264411505 372 10,950 SH   SOLE   10,950 0 0
EAST WEST BANCORP INC COM 27579r104 332 7,500 SH   SOLE   7,500 0 0
ECOLAB INC COM 278865100 238,369 1,203,640 SH   SOLE   1,203,640 0 0
EDWARDS LIFESCIENCES COM 28176e108 2,880 13,096 SH   SOLE   13,096 0 0
ELI LILLY & CO COM 532457108 797 7,129 SH   SOLE   7,129 0 0
EMERSON ELECTRIC CO COM 291011104 704 10,526 SH   SOLE   10,526 0 0
ENTERPRISE PRDTS PRTN LPL P COM 293792107 1,226 42,911 SH   SOLE   42,911 0 0
ENVESTNET INC COM 29404K106 69,623 1,227,927 SH   SOLE   1,227,927 0 0
EQUITY RESIDENTIAL REIT COM 29476l107 313 3,626 SH   SOLE   3,626 0 0
EVENTBRITE INC COM 29975e109 2,808 158,556 SH   SOLE   158,556 0 0
EVERTEC INC COM 30040P103 3,507 112,325 SH   SOLE   112,325 0 0
EVO PAYMENTS INC COM 26927e104 9,201 327,216 SH   SOLE   327,216 0 0
EXACT SCIENCES CORP COM COM 30063p105 271 3,000 SH   SOLE   3,000 0 0
EXELON CORP COM COM 30161N101 215 4,444 SH   SOLE   4,444 0 0
EXPONENT INC COM 30214U102 4,681 66,963 SH   SOLE   66,963 0 0
EXXON MOBIL CORP COM COM 30231g102 1,770 25,062 SH   SOLE   25,062 0 0
FACEBOOK INC CLASS COM 30303m102 280 1,572 SH   SOLE   1,572 0 0
FASTENAL CO COM 311900104 145,741 4,461,015 SH   SOLE   4,461,015 0 0
FISERV INC COM 337738108 6,537 63,100 SH   SOLE   63,100 0 0
FORTINET INC COM COM 34959E109 788 10,263 SH   SOLE   10,263 0 0
GENERAL ELECTRIC COM 369604103 467 52,229 SH   SOLE   52,229 0 0
GENESEE AND WYOMING INC COM 371559105 9,154 82,835 SH   SOLE   82,835 0 0
GENUINE PARTS CO COM 372460105 317 3,179 SH   SOLE   3,179 0 0
GLAXOSMITHKLINE PLC SPONSORED COM 37733W105 216 5,063 SH   SOLE   5,063 0 0
GLU MOBILE INC COM 379890106 62 12,500 SH   SOLE   12,500 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 9,734 92,368 SH   SOLE   92,368 0 0
HAMILTON LANE INC COM 407497106 8,469 148,679 SH   SOLE   148,679 0 0
HD SUPPLY HOLDINGS INC COM 40416M105 886 22,621 SH   SOLE   22,621 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 27,744 1,142,190 SH   SOLE   1,142,190 0 0
HEALTHPEAK PPTYS INC COM 42250p103 1,686 47,325 SH   SOLE   47,325 0 0
HEICO CORP CL A COM 422806208 9,085 93,360 SH   SOLE   93,360 0 0
HELIOS TECHNOLOGIES ORD SHS COM 42328h109 3,804 93,760 SH   SOLE   93,760 0 0
HOME DEPOT INC COM 437076102 611 2,634 SH   SOLE   2,634 0 0
HONEYWELL INTL INC COM 438516106 3,243 19,166 SH   SOLE   19,166 0 0
IAA INC. COM 449253103 2,806 67,232 SH   SOLE   67,232 0 0
IBM CORP COM 459200101 1,217 8,370 SH   SOLE   8,370 0 0
IDEXX LABORATORIES INC COM 45168D104 27,877 102,516 SH   SOLE   102,516 0 0
ILLINOIS TOOL WORKS COM 452308109 325 2,074 SH   SOLE   2,074 0 0
ILLUMINA INC COM 452327109 166,118 546,045 SH   SOLE   546,045 0 0
INTEL CORP COM 458140100 14,595 283,234 SH   SOLE   283,234 0 0
INTUITIVE SURGICAL INC COM 46120E602 141,525 262,117 SH   SOLE   262,117 0 0
JOHN BEAN TECHNOLOGIES COM 477839104 6,065 61,000 SH   SOLE   61,000 0 0
JOHNSON AND JOHNSON COM COM 478160104 12,123 93,704 SH   SOLE   93,704 0 0
JPMORGAN CHASE & CO COM 46625h100 4,991 42,404 SH   SOLE   42,404 0 0
KANSAS CITY SOUTHERN COM NEW COM 485170302 2,150 16,165 SH   SOLE   16,165 0 0
KEYCORP COM 493267108 241 13,500 SH   SOLE   13,500 0 0
KEYON COMMUNI HOLD INC COM 493312201 0 16,667 SH   SOLE   16,667 0 0
KEYSIGHT TECHNOLOGIES INC COM 49338l103 2,625 26,992 SH   SOLE   26,992 0 0
KIMBERLY CLARK COM 494368103 385 2,713 SH   SOLE   2,713 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 1,577 9,384 SH   SOLE   9,384 0 0
LEMAITRE VASCULAR COM 525558201 3,627 106,101 SH   SOLE   106,101 0 0
LINCOLN NTL CORP IND NPV COM 534187109 640 10,603 SH   SOLE   10,603 0 0
LITTELFUSE INC COM 537008104 3,784 21,340 SH   SOLE   21,340 0 0
LOWE'S COMPANIES INC COM 548661107 3,982 36,217 SH   SOLE   36,217 0 0
M & T BANK CORP COM 55261f104 522 3,302 SH   SOLE   3,302 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 408 6,150 SH   SOLE   6,150 0 0
MARKEL CORP HLDG CO COM 570535104 199,543 168,832 SH   SOLE   168,832 0 0
MASTERCARD INC-CLASS A COM 57636Q104 122,670 451,705 SH   SOLE   451,705 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,962 12,555 SH   SOLE   12,555 0 0
MCDONALDS CORP COM COM 580135101 756 3,520 SH   SOLE   3,520 0 0
MERCK AND CO INC SHS COM 58933y105 4,592 54,552 SH   SOLE   54,552 0 0
MESA LABS INC COM 59064R109 9,452 39,752 SH   SOLE   39,752 0 0
MGP INGREDIENTS INC COM 55303J106 3,604 72,546 SH   SOLE   72,546 0 0
MICROSOFT CORP COM 594918104 15,017 108,013 SH   SOLE   108,013 0 0
MIDDLEBY CORP COM 596278101 5,789 49,520 SH   SOLE   49,520 0 0
MOHAWK INDS INC COM COM 608190104 1,321 10,645 SH   SOLE   10,645 0 0
MONRO INC COM 610236101 7,479 94,655 SH   SOLE   94,655 0 0
MOODYS CORP COM 615369105 167,925 819,826 SH   SOLE   819,826 0 0
NASPERS SPON ADR EACH REP 0.2 COM 631512209 204 6,750 SH   SOLE   6,750 0 0
NEOGEN CORP COM COM 640491106 845 12,400 SH   SOLE   12,400 0 0
NESTLE S A REP RG SH ADR COM 641069406 667 6,142 SH   SOLE   6,142 0 0
NORFOLK SOUTHERN CO COM 655844108 3,022 16,819 SH   SOLE   16,819 0 0
NOVANTA INC COM NPV COM 67000b104 8,614 105,409 SH   SOLE   105,409 0 0
NOVARTIS ADR COM 66987v109 459 5,285 SH   SOLE   5,285 0 0
NUTRIEN LTD COM 67077m108 1,215 24,365 SH   SOLE   24,365 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 18,687 46,892 SH   SOLE   46,892 0 0
OKTA, INC COM 679295105 55,586 564,558 SH   SOLE   564,558 0 0
ORACLE CORPORATION COM 68389x105 284 5,165 SH   SOLE   5,165 0 0
ORTHOPEDIATRICS CORP COM 68752L100 10,444 296,211 SH   SOLE   296,211 0 0
PAYCHEX INC COM 704326107 3,959 47,830 SH   SOLE   47,830 0 0
PEPSICO INC COM 713448108 1,700 12,402 SH   SOLE   12,402 0 0
PFIZER INC COM 717081103 2,004 55,789 SH   SOLE   55,789 0 0
PHILLIPS 66 COM 718546104 222 2,170 SH   SOLE   2,170 0 0
PINNACLE WEST CAP CORP COM 723484101 291 3,000 SH   SOLE   3,000 0 0
PNC FINCL SERVICES GROUP COM 693475105 1,048 7,479 SH   SOLE   7,479 0 0
POOL CORPORATION COM 73278l105 625 3,098 SH   SOLE   3,098 0 0
PRICE T ROWE GROUP INC COM 74144T108 11,733 102,693 SH   SOLE   102,693 0 0
PROCTER & GAMBLE CO COM 742718109 18,199 146,317 SH   SOLE   146,317 0 0
PROS HOLDINGS INC COM 74346Y103 128,779 2,160,719 SH   SOLE   2,160,719 0 0
QUALCOMM INC COM 747525103 25,263 331,190 SH   SOLE   331,190 0 0
QUALYS INC COM COM 74758t303 66,431 879,070 SH   SOLE   879,070 0 0
REALTY INCM CRP MD PV$1.REIT COM 756109104 217 2,832 SH   SOLE   2,832 0 0
ROPER TECHNOLOGIES INC COM 776696106 193,639 543,015 SH   SOLE   543,015 0 0
RPM INTERNATIONAL INC COM 749685103 287 4,175 SH   SOLE   4,175 0 0
S & P GLOBAL INC COM 78409V104 132,240 539,800 SH   SOLE   539,800 0 0
SBA COMMUNICATIONS CORP CL A COM 78410G104 82,963 344,032 SH   SOLE   344,032 0 0
SCHLUMBERGER LTD COM 806857108 2,229 65,221 SH   SOLE   65,221 0 0
SEI INVESTMENTS CO COM 784117103 14,287 241,107 SH   SOLE   241,107 0 0
SERVICE CORP INTL COM 817565104 311 6,500 SH   SOLE   6,500 0 0
SITEONE LANDSCAPE SUPPLY, INC. COM 82982L103 9,060 122,394 SH   SOLE   122,394 0 0
SOUTHERN COMPANY COM 842587107 242 3,925 SH   SOLE   3,925 0 0
STANLEY BLACK & DECK COM 854502101 247 1,710 SH   SOLE   1,710 0 0
STERIS PLC COM G8473t100 918 6,351 SH   SOLE   6,351 0 0
STRYKER CORP COM 863667101 201 930 SH   SOLE   930 0 0
TE CONNECTIVITY LTD F COM h84989104 1,659 17,801 SH   SOLE   17,801 0 0
TELADOC INC COM 87918A105 6,434 95,009 SH   SOLE   95,009 0 0
TELEFLEX INC COM COM 879369106 91,147 268,276 SH   SOLE   268,276 0 0
THE BOEING CO COM 097023105 318 837 SH   SOLE   837 0 0
THE DESCARTES SYSTEMS GROUP IN COM 249906108 2,726 67,622 SH   SOLE   67,622 0 0
THERMO FISHER SCIENTIFIC INC COM 883556102 93,293 320,297 SH   SOLE   320,297 0 0
TRACTOR SUPPLY COMP COM 892356106 849 9,389 SH   SOLE   9,389 0 0
TRANSDIGM GROUP INC COM 893641100 144,995 278,478 SH   SOLE   278,478 0 0
TRANSUNION COM 89400j107 25,060 308,958 SH   SOLE   308,958 0 0
TREX COMPANY, INC. COM 89531P105 4,974 54,699 SH   SOLE   54,699 0 0
TRIMBLE INC COM 896239100 51,799 1,334,676 SH   SOLE   1,334,676 0 0
TRUPANION, INC. COM 898202106 4,232 166,493 SH   SOLE   166,493 0 0
TYLER TECHNOLOGIES INC COM 902252105 205,505 782,875 SH   SOLE   782,875 0 0
U S BANCORP COM 902973304 1,504 27,174 SH   SOLE   27,174 0 0
UNION PACIFIC CORP COM 907818108 272 1,680 SH   SOLE   1,680 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 319 2,666 SH   SOLE   2,666 0 0
UNITED TECHNOLOGIES CORP. COM 913017109 884 6,475 SH   SOLE   6,475 0 0
UNITEDHEALTH GRP INC COM 91324p102 1,593 7,332 SH   SOLE   7,332 0 0
VAPOTHERM INC COM 922107107 1,803 190,433 SH   SOLE   190,433 0 0
VENTAS INC REIT COM 92276f100 1,484 20,324 SH   SOLE   20,324 0 0
VERISK ANALYTICS INC COM 92345Y106 233,439 1,476,152 SH   SOLE   1,476,152 0 0
VERIZON COMMUNICATIONS INC COM 92343v104 962 15,944 SH   SOLE   15,944 0 0
VISA INC CL A COM 92826C839 212,185 1,233,563 SH   SOLE   1,233,563 0 0
VULCAN MATERIALS CO COM 929160109 175,563 1,160,821 SH   SOLE   1,160,821 0 0
W.P. CAREY INC. REIT COM 92936u109 456 5,095 SH   SOLE   5,095 0 0
WALMART STORES COM 931142103 527 4,441 SH   SOLE   4,441 0 0
WASTE CONNECTIONS INC COM 94106B101 176,796 1,921,691 SH   SOLE   1,921,691 0 0
WATSCO INC COM 942622200 12,030 71,106 SH   SOLE   71,106 0 0
WAYFAIR COM 94419L101 5,595 49,905 SH   SOLE   49,905 0 0
WD-40 COMPANY COM 929236107 3,057 16,654 SH   SOLE   16,654 0 0
WESTINGHOUSE AIR BRAKE TECHNOL COM 929740108 1,998 27,800 SH   SOLE   27,800 0 0
WSFS FINANCIAL CORP COM 929328102 341 7,739 SH   SOLE   7,739 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 92 10,000 SH   SOLE   10,000 0 0
ISHARES CORE S&P 500 ETF ETFS 464287200 877 2,938 SH   SOLE   2,938 0 0
ISHARES CORE S&P MID CAP ETF ETFS 464287507 1,127 5,834 SH   SOLE   5,834 0 0
ISHARES CORE S&P SMALL CAP ETF ETFS 464287804 491 6,303 SH   SOLE   6,303 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 813 12,472 SH   SOLE   12,472 0 0
ISHARES TR MSCI EMG MKT ETF ETFS 464287234 204 4,999 SH   SOLE   4,999 0 0
SPDR GOLD TRUST ETFS 78463v107 213 1,533 SH   SOLE   1,533 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 1,297 10,843 SH   SOLE   10,843 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 3,310 66,328 SH   SOLE   66,328 0 0
VANGUARD FTSE EMERGING MARK ET ETFS 922042858 920 22,843 SH   SOLE   22,843 0 0
VANGUARD HIGH DIVIDEND YIELD E ETFS 921946406 708 7,976 SH   SOLE   7,976 0 0
VANGUARD REIT ETF ETFS 922908553 1,216 13,040 SH   SOLE   13,040 0 0
VANGUARD S&P 500 ETF ETFS 922908363 5,210 19,114 SH   SOLE   19,114 0 0
VANGUARD TOTAL STK MKT ETF ETFS 922908769 395 2,615 SH   SOLE   2,615 0 0
WISDOMTREE TR INDIA ERNGS FD ETFS 97717W422 215 9,000 SH   SOLE   9,000 0 0