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 Maerten's daughter Maria Maertens Leeuwenhoek (1656-1717), widow of Jan den Appel, living on Pontemarkt, buried in Nieuwe Kerk
DTB Delft inv. 47, fol. 257v