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 298 60,625 SH   SOLE   60,625 0 0
3M COMPANY COM 88579y101 1,417 8,846 SH   SOLE   8,846 0 0
AAC HOLDINGS INC COM 000307108 5 182,000 SH   SOLE   182,000 0 0
ABBOTT LABORATORIES COM 002824100 2,447 22,481 SH   SOLE   22,481 0 0
ABBVIE INC SHS COM 00287y109 895 10,213 SH   SOLE   10,213 0 0
ACCENTURE PLC F CLASS A COM g1151c101 426 1,883 SH   SOLE   1,883 0 0
ADOBE SYSTEMS INC COM 00724F101 244 498 SH   SOLE   498 0 0
AIR PROD & CHEMICALS COM 009158106 826 2,773 SH   SOLE   2,773 0 0
ALARM.COM COM 011642105 5,112 92,523 SH   SOLE   92,523 0 0
ALPHABET INC CLASS C COM 02079K107 135,306 92,070 SH   SOLE   92,070 0 0
ALPHABET INC. CLASS A COM 02079k305 1,943 1,326 SH   SOLE   1,326 0 0
AMAZON.COM INC COM 023135106 187,186 59,448 SH   SOLE   59,448 0 0
AMERICAN TOWER CORP COM 03027X100 148,482 614,248 SH   SOLE   614,248 0 0
AMGEN INC. COM 031162100 985 3,876 SH   SOLE   3,876 0 0
AMPHENOL CORP NEW CL A COM 032095101 327 3,018 SH   SOLE   3,018 0 0
ANALOG DEVICES INC COM 032654105 286 2,448 SH   SOLE   2,448 0 0
ANSYS INC COM 03662Q105 302,037 923,010 SH   SOLE   923,010 0 0
APPLE INC COM 037833100 14,486 125,082 SH   SOLE   125,082 0 0
ASPEN TECHNOLOGY, INC. COM 045327103 4,504 35,577 SH   SOLE   35,577 0 0
ATLASSIAN CORPORATION PLC COM G06242104 47,594 261,808 SH   SOLE   261,808 0 0
ATRION CORPORATION COM 049904105 9,010 14,393 SH   SOLE   14,393 0 0
AUTO DATA PROCESSING COM 053015103 1,908 13,680 SH   SOLE   13,680 0 0
BANK AMER CORP COM COM 060505104 349 14,472 SH   SOLE   14,472 0 0
BECTON DICKINSON&CO COM 075887109 449 1,928 SH   SOLE   1,928 0 0
BERKLEY W R CORP COM 084423102 1,329 21,736 SH   SOLE   21,736 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 2,240 7 SH   SOLE   7 0 0
BERKSHIRE HATHAWAY INC CL B COM 084670702 7,626 35,812 SH   SOLE   35,812 0 0
BIO-TECHNE CORP COM 09073M104 222,818 899,437 SH   SOLE   899,437 0 0
BLACK KNIGHT INC COM 09215C105 167,185 1,920,563 SH   SOLE   1,920,563 0 0
BLACKLINE INC COM 09239B109 228,489 2,549,250 SH   SOLE   2,549,250 0 0
BRIGHT HORIZONS FAM SOL IN DEL COM 109194100 57,886 380,726 SH   SOLE   380,726 0 0
BRISTOL-MYERS SQUIBB COM 110122108 232 3,851 SH   SOLE   3,851 0 0
BROADRIDGE FINL SOLUTIONS COM 11133T103 292 2,214 SH   SOLE   2,214 0 0
BROOKS AUTOMATION INC COM 114340102 55,657 1,203,129 SH   SOLE   1,203,129 0 0
C M S ENERGY CORP COM 125896100 342 5,568 SH   SOLE   5,568 0 0
CABLE ONE INC COM COM 12685J105 199,999 106,076 SH   SOLE   106,076 0 0
CALAVO GROWERS INC COM 128246105 4,665 70,398 SH   SOLE   70,398 0 0
CANADIAN NATL RAILWY F COM 136375102 1,544 14,500 SH   SOLE   14,500 0 0
CANTEL MEDICAL CORP COM 138098108 3,284 74,737 SH   SOLE   74,737 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 1,525 21,216 SH   SOLE   21,216 0 0
CARMAX INC COM 143130102 148,099 1,611,350 SH   SOLE   1,611,350 0 0
CBRE GROUP INC COM 12504L109 141,928 3,021,680 SH   SOLE   3,021,680 0 0
CDW CORP COM COM 12514G108 320 2,676 SH   SOLE   2,676 0 0
CHARTER COMMUNICATIONS, INC. COM 16119p108 209 335 SH   SOLE   335 0 0
CHEVRON CORP COM 166764100 305 4,238 SH   SOLE   4,238 0 0
CHUBB LTD COM h1467j104 466 4,010 SH   SOLE   4,010 0 0
CISCO SYSTEMS INC COM 17275r102 2,562 65,044 SH   SOLE   65,044 0 0
COCA COLA COM COM 191216100 1,953 39,553 SH   SOLE   39,553 0 0
COGENT COMMUNICATIONS COM 19239V302 9,428 156,997 SH   SOLE   156,997 0 0
COLGATE-PALMOLIVE CO COM 194162103 849 11,000 SH   SOLE   11,000 0 0
COMCAST CORP NEW CL A COM 20030n101 3,280 70,897 SH   SOLE   70,897 0 0
CONSTELLATION SOFTWR F COM 21037x100 8,227 7,399 SH   SOLE   7,399 0 0
COSTAR GROUP INC COM 22160N109 190,358 224,344 SH   SOLE   224,344 0 0
COSTCO WHOLESALE CO COM 22160k105 844 2,377 SH   SOLE   2,377 0 0
COUPA SOFTWARE COM 22266l106 21,523 78,484 SH   SOLE   78,484 0 0
CROWDSTRIKE HOLDINGS, INC. COM 22788c105 7,010 51,050 SH   SOLE   51,050 0 0
CROWN CASTLE REIT INC COM 22822v101 9,084 54,557 SH   SOLE   54,557 0 0
CVS HEALTH CORP COM 126650100 293 5,016 SH   SOLE   5,016 0 0
DANAHER CORP COM 235851102 159,748 741,874 SH   SOLE   741,874 0 0
DISCOVER FINANCIAL SERVICES COM 254709108 1,220 21,122 SH   SOLE   21,122 0 0
DOLLAR GENERAL CORP COM 256677105 37,865 180,637 SH   SOLE   180,637 0 0
DOUGLAS DYNAMICS INC COM 25960R105 12,902 377,259 SH   SOLE   377,259 0 0
DUKE REALTY CORP REIT COM 264411505 303 8,200 SH   SOLE   8,200 0 0
EAST WEST BANCORP INC COM 27579r104 265 8,100 SH   SOLE   8,100 0 0
ECOLAB INC COM 278865100 240,896 1,205,444 SH   SOLE   1,205,444 0 0
EDWARDS LIFESCIENCES COM 28176e108 2,751 34,463 SH   SOLE   34,463 0 0
EMERSON ELECTRIC CO COM 291011104 445 6,793 SH   SOLE   6,793 0 0
ENTERPRISE PRODS PART LP COM 293792107 627 39,712 SH   SOLE   39,712 0 0
ENVESTNET INC COM 29404K106 109,867 1,423,885 SH   SOLE   1,423,885 0 0
EVERTEC INC COM 30040P103 6,418 184,900 SH   SOLE   184,900 0 0
EVO PAYMENTS INC COM 26927e104 10,895 438,420 SH   SOLE   438,420 0 0
EXACT SCIENCES CORP COM COM 30063p105 275 2,700 SH   SOLE   2,700 0 0
EXPONENT INC COM 30214U102 7,521 104,417 SH   SOLE   104,417 0 0
EXXON MOBIL CORP COM 30231g102 644 18,748 SH   SOLE   18,748 0 0
FACEBOOK INC CLASS COM 30303m102 543 2,072 SH   SOLE   2,072 0 0
FASTENAL CO COM 311900104 186,426 4,134,542 SH   SOLE   4,134,542 0 0
FISERV INC COM 337738108 5,400 52,406 SH   SOLE   52,406 0 0
FLOOR & DECOR HOLDINGS, INC. COM 339750101 13,261 177,282 SH   SOLE   177,282 0 0
FORTINET INC COM COM 34959E109 1,209 10,263 SH   SOLE   10,263 0 0
GENUINE PARTS CO COM 372460105 226 2,379 SH   SOLE   2,379 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 12,606 120,899 SH   SOLE   120,899 0 0
HAMILTON LANE INC COM 407497106 11,514 178,258 SH   SOLE   178,258 0 0
HEALTHEQUITY, INC. COM 42226A107 6,605 128,582 SH   SOLE   128,582 0 0
HEALTHPEAK PPTYS INC COM 42250p103 1,168 43,029 SH   SOLE   43,029 0 0
HEICO CORP CL A COM 422806208 115,690 1,304,867 SH   SOLE   1,304,867 0 0
HELIOS TECHNOLOGIES ORD SHS COM 42328h109 3,924 107,806 SH   SOLE   107,806 0 0
HOME DEPOT INC COM 437076102 1,149 4,138 SH   SOLE   4,138 0 0
HONEYWELL INTL INC COM 438516106 804 4,885 SH   SOLE   4,885 0 0
IAA INC. COM 449253103 13,974 268,371 SH   SOLE   268,371 0 0
IBM CORP COM 459200101 499 4,098 SH   SOLE   4,098 0 0
IDEX CORP COM 45167R104 3,952 21,667 SH   SOLE   21,667 0 0
IDEXX LABS INC COM 45168d104 100,070 254,559 SH   SOLE   254,559 0 0
ILLINOIS TOOL WORKS COM 452308109 423 2,187 SH   SOLE   2,187 0 0
ILLUMINA INC COM 452327109 208,268 673,831 SH   SOLE   673,831 0 0
INTEL CORP COM 458140100 13,459 259,929 SH   SOLE   259,929 0 0
INTUITIVE SURGICAL INC COM 46120E602 226,782 319,619 SH   SOLE   319,619 0 0
J P MORGAN CHASE & CO COM 46625h100 4,745 49,290 SH   SOLE   49,290 0 0
JOHN BEAN TECHNOLOGIES COM 477839104 7,117 77,447 SH   SOLE   77,447 0 0
JOHNSON AND JOHNSON COM COM 478160104 12,817 86,087 SH   SOLE   86,087 0 0
KANSAS CITY SOUTHERN COM NEW COM 485170302 2,537 14,030 SH   SOLE   14,030 0 0
KEYON COMMUNI HOLD INC COM 493312201 0 16,667 SH   SOLE   16,667 0 0
KEYSIGHT TECHNOLOGIES INC COM 49338l103 1,964 19,887 SH   SOLE   19,887 0 0
KIMBERLY-CLARK CORP COM 494368103 415 2,813 SH   SOLE   2,813 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 1,761 9,354 SH   SOLE   9,354 0 0
LEMAITRE VASCULAR COM 525558201 6,227 191,415 SH   SOLE   191,415 0 0
LILLY ELI & CO COM 532457108 962 6,501 SH   SOLE   6,501 0 0
LITTELFUSE INC COM 537008104 3,960 22,329 SH   SOLE   22,329 0 0
LOWE'S COMPANIES INC COM 548661107 4,439 26,762 SH   SOLE   26,762 0 0
M & T BANK CORP COM 55261f104 340 3,697 SH   SOLE   3,697 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 503 14,708 SH   SOLE   14,708 0 0
MARKEL CORP HLDG CO COM 570535104 216,004 221,838 SH   SOLE   221,838 0 0
MARSH & MC LENNAN COMPANIES IN COM 571748102 260 2,265 SH   SOLE   2,265 0 0
MASTERCARD INC-CLASS A COM 57636Q104 166,856 493,407 SH   SOLE   493,407 0 0
MC DONALDS CORP COM 580135101 762 3,470 SH   SOLE   3,470 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 2,262 11,655 SH   SOLE   11,655 0 0
MEDTRONIC PLC F COM g5960l103 299 2,876 SH   SOLE   2,876 0 0
MERCK & CO. INC. COM 58933y105 4,298 51,818 SH   SOLE   51,818 0 0
MERGENET SOLUTIONS INC COM COM 58950m109 10 10,000 SH   SOLE   10,000 0 0
MESA LABS INC COM 59064R109 11,620 45,613 SH   SOLE   45,613 0 0
MICROSOFT CORP COM 594918104 23,913 113,693 SH   SOLE   113,693 0 0
MIDDLEBY CORP COM 596278101 2,750 30,658 SH   SOLE   30,658 0 0
MONDELEZ INTL INC COM 609207105 423 7,365 SH   SOLE   7,365 0 0
MONRO INC COM 610236101 6,284 154,903 SH   SOLE   154,903 0 0
MOODYS CORP COM 615369105 215,823 744,602 SH   SOLE   744,602 0 0
NASPERS SPON ADR EACH REP 0.2 COM 631512209 240 6,750 SH   SOLE   6,750 0 0
NEOGEN CORP COM COM 640491106 923 11,800 SH   SOLE   11,800 0 0
NESTLE S A F SPONSORED ADR 1 A COM 641069406 951 7,974 SH   SOLE   7,974 0 0
NEWMONT GOLDCORP CORP COM 651639106 301 4,749 SH   SOLE   4,749 0 0
NEXTERA ENERGY INC SHS COM 65339f101 526 1,895 SH   SOLE   1,895 0 0
NORFOLK SOUTHERN CO COM 655844108 3,432 16,036 SH   SOLE   16,036 0 0
NOVANTA INC COM NPV COM 67000b104 10,570 100,343 SH   SOLE   100,343 0 0
NOVARTIS AG F SPONSORED ADR 1 COM 66987v109 476 5,475 SH   SOLE   5,475 0 0
NUTRIEN LTD COM 67077m108 2,055 52,380 SH   SOLE   52,380 0 0
O REILLY AUTOMOTIVE COM 67103h107 19,956 43,282 SH   SOLE   43,282 0 0
OKTA, INC COM 679295105 96,846 452,867 SH   SOLE   452,867 0 0
OLD DOMINION FGHT LINES INC CO COM 679580100 32,076 177,293 SH   SOLE   177,293 0 0
ORTHOPEDIATRICS CORP COM 68752L100 16,725 364,215 SH   SOLE   364,215 0 0
PAYCHEX INC COM 704326107 3,481 43,638 SH   SOLE   43,638 0 0
PEPSICO INC COM 713448108 1,698 12,250 SH   SOLE   12,250 0 0
PFIZER INC COM 717081103 2,457 66,950 SH   SOLE   66,950 0 0
PINNACLE WEST CAP CORP COM 723484101 224 3,000 SH   SOLE   3,000 0 0
PNC FINL SERVICES COM 693475105 447 4,071 SH   SOLE   4,071 0 0
POOL CORPORATION COM 73278l105 886 2,648 SH   SOLE   2,648 0 0
PRICE T ROWE GROUP INC COM 74144T108 12,123 94,551 SH   SOLE   94,551 0 0
PROCTER & GAMBLE CO COM 742718109 19,997 143,871 SH   SOLE   143,871 0 0
PROS HOLDINGS INC COM 74346Y103 111,930 3,504,376 SH   SOLE   3,504,376 0 0
QUALCOMM INC COM 747525103 38,839 330,043 SH   SOLE   330,043 0 0
QUALYS INC COM COM 74758t303 90,376 922,111 SH   SOLE   922,111 0 0
RAYTHEON TECHNOLOGIES ORD SHS COM 75513e101 378 6,567 SH   SOLE   6,567 0 0
REALTY INCM CRP MD PV$1.REIT COM 756109104 288 4,740 SH   SOLE   4,740 0 0
REPLIGEN CORPORATION COM 759916109 6,730 45,612 SH   SOLE   45,612 0 0
REPUBLIC SVCS INC COM 760759100 268 2,870 SH   SOLE   2,870 0 0
ROPER TECHNOLOGIES INC COM 776696106 228,187 577,528 SH   SOLE   577,528 0 0
RPM INTERNATIONAL INC COM 749685103 346 4,175 SH   SOLE   4,175 0 0
S & P GLOBAL INC COM 78409V104 161,884 448,929 SH   SOLE   448,929 0 0
SALESFORCE.COM INC COM 79466L302 312 1,242 SH   SOLE   1,242 0 0
SBA COMMUNICATIONS CORP CL A COM 78410G104 126,603 397,522 SH   SOLE   397,522 0 0
SEI INVESTMENTS CO COM 784117103 353 6,953 SH   SOLE   6,953 0 0
SERVICE CORP INTL COM 817565104 479 11,354 SH   SOLE   11,354 0 0
SITEONE LANDSCAPE SUPPLY, INC. COM 82982L103 13,003 106,622 SH   SOLE   106,622 0 0
STERIS PLC COM G8473t100 278 1,576 SH   SOLE   1,576 0 0
TELADOC INC COM 87918A105 10,450 47,665 SH   SOLE   47,665 0 0
TELEFLEX INC COM COM 879369106 157,181 461,728 SH   SOLE   461,728 0 0
THE DESCARTES SYSTEMS GROUP IN COM 249906108 7,402 129,908 SH   SOLE   129,908 0 0
THERMO FISHER SCIENTIFIC INC COM 883556102 144,714 327,764 SH   SOLE   327,764 0 0
TRANSDIGM GROUP INC COM 893641100 163,861 344,884 SH   SOLE   344,884 0 0
TREX COMPANY, INC. COM 89531P105 17,182 239,970 SH   SOLE   239,970 0 0
TRIMBLE INC COM 896239100 566 11,615 SH   SOLE   11,615 0 0
TRUPANION, INC. COM 898202106 10,952 138,808 SH   SOLE   138,808 0 0
TWILIO INC. COM 90138F102 65,123 263,560 SH   SOLE   263,560 0 0
TYLER TECHNOLOGIES INC COM 902252105 111,285 319,271 SH   SOLE   319,271 0 0
U S BANCORP COM 902973304 875 24,420 SH   SOLE   24,420 0 0
UNION PACIFIC CORP COM 907818108 255 1,296 SH   SOLE   1,296 0 0
UNITED PARCEL SRVC CLASS B COM 911312106 432 2,591 SH   SOLE   2,591 0 0
UNITEDHEALTH GRP INC COM 91324p102 2,463 7,901 SH   SOLE   7,901 0 0
VEEVA SYSTEMS, INC. COM 922475108 111,100 395,107 SH   SOLE   395,107 0 0
VENTAS INC REIT COM 92276f100 811 19,324 SH   SOLE   19,324 0 0
VERISK ANALYTICS INC COM 92345Y106 241,786 1,304,763 SH   SOLE   1,304,763 0 0
VERIZON COMMUNICATN COM 92343v104 1,026 17,242 SH   SOLE   17,242 0 0
VISA INC CL A COM 92826C839 234,380 1,172,075 SH   SOLE   1,172,075 0 0
VULCAN MATERIALS CO COM 929160109 212,709 1,569,345 SH   SOLE   1,569,345 0 0
W.P. CAREY INC. REIT COM 92936u109 367 5,625 SH   SOLE   5,625 0 0
WABTEC COM 929740108 2,611 42,200 SH   SOLE   42,200 0 0
WALMART INC COM 931142103 691 4,941 SH   SOLE   4,941 0 0
WALT DISNEY CO COM 254687106 949 7,651 SH   SOLE   7,651 0 0
WASTE CONNECTIONS INC COM 94106B101 290,105 2,794,841 SH   SOLE   2,794,841 0 0
WATSCO INC COM 942622200 5,253 22,554 SH   SOLE   22,554 0 0
WAYFAIR COM 94419L101 8,065 27,714 SH   SOLE   27,714 0 0
WD-40 COMPANY COM 929236107 3,618 19,109 SH   SOLE   19,109 0 0
WELLS FARGO BK N A COM 949746101 2,020 85,934 SH   SOLE   85,934 0 0
GLOBAL X SILVER MINERS ETF ETFS 26924g102 590 42,700 SH   SOLE   42,700 0 0
ISHARES CORE S&P 500 ETF ETFS 464287200 1,069 3,180 SH   SOLE   3,180 0 0
ISHARES CORE S&P MID CAP ETF ETFS 464287507 855 4,616 SH   SOLE   4,616 0 0
ISHARES CORE S&P SMALL CAP ETF ETFS 464287804 447 6,368 SH   SOLE   6,368 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 646 10,157 SH   SOLE   10,157 0 0
ISHARES MSCI GLOBAL SILVER & M ETFS 464286327 421 27,000 SH   SOLE   27,000 0 0
SPDR FUND CONSUMER DISCRE SELE ETFS 81369y407 215 1,466 SH   SOLE   1,466 0 0
SPDR GOLD TRUST ETFS 78463v107 272 1,533 SH   SOLE   1,533 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 1,417 11,017 SH   SOLE   11,017 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 3,190 63,232 SH   SOLE   63,232 0 0
VANGUARD FTSE EMERGING MARKETS ETFS 922042858 754 17,436 SH   SOLE   17,436 0 0
VANGUARD HEALTH CARE ETFS 92204a504 246 1,204 SH   SOLE   1,204 0 0
VANGUARD HIGH DIVIDEND YIELD E ETFS 921946406 811 10,021 SH   SOLE   10,021 0 0
VANGUARD INDEX FDS SMALL CP ET ETFS 922908751 360 2,341 SH   SOLE   2,341 0 0
VANGUARD INFO TECHNOLOGY INDEX ETFS 92204a702 330 1,058 SH   SOLE   1,058 0 0
VANGUARD MID CAP ETF ETFS 922908629 446 2,533 SH   SOLE   2,533 0 0
VANGUARD REIT ETF ETFS 922908553 1,172 14,846 SH   SOLE   14,846 0 0
VANGUARD S&P 500 ETF ETFS 922908363 4,880 15,861 SH   SOLE   15,861 0 0
VANGUARD TOTAL STK MKT ETF ETFS 922908769 554 3,253 SH   SOLE   3,253 0 0
WISDOMTREE TR INDIA ERNGS FD ETFS 97717W422 212 9,000 SH   SOLE   9,000 0 0