Volumes 1 through 20 of Alle de Brieven / Collected Letters, the complete series. Download for free.
Master list (pdf) of all 602 L-numbers, their Leeuwenhoek number, and their Collected Letters number
cousin Jannitgen Huijchs Leeuwenhoek (1633-1681) buried in Nieuwe Kerk
DTB Delft inv. 43