http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-search.pl?q=ccl=Provider%3AWillett%2C%20Clark%20%26%20Co.%2C&format=rss2 4 0 50 ISBN http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=8825 By Knox, John, 1900-1990 . Chicago : Willett, Clark & Co., 1942 . 100 p. ; 19 cm..

]]> http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=8825 ISBN http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=6318 Chicago : Willett, Clark & Co., 1938 . xii, 315 p. ; 20 cm..

]]> http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=6318 ISBN http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=1396 By Barclay, Wade Crawford, 1874-1965. Chicago : Willett, Clark & Co., 1945 . 257 p. ; 20 cm..

]]> http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=1396 ISBN http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=10769 By Knox, John, 1900-1990. Chicago : Willett, Clark & Co., 1945 . 146 p. ; 21 cm..

]]> http://biblioteca.ubl.ac.cr/cgi-bin/koha/opac-detail.pl?biblionumber=10769