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
Baptism of Cornelis, first child of Isaac Arents van Gravesande and Annetgen Cornelis. The witnesses were Jehan Steenhuijsen and Neeltgen Steenhuijsen.
DTB inv 8, fol 95