Some information can be found here about van Laer:
New York State Library:
http://www.nysl.nysed.gov/msscfa/sc15317.htm
https://exhibitions.nysm.nysed.gov/albany/bios/staff/ajfvlaer.html
Wikipedia:
https://en.wikipedia.org/wiki/Arnold_Johan_Ferdinand_Van_Laer
From the New York State Library website:
Arnold Johan Ferdinand (A.J.F.) van Laer was a librarian and archivist with the New York State Library (1899-1915) and the Division of History and Archives (1915-1939), best known for his translations of New York's colonial Dutch records. Published works include four volumes of New Netherland records, two of Beverwyck, six of Albany County, four relating to Rensselaerswyck, and one of Lutheran records in Holland relative to the Colony of New York.