More than 50 different perfin for this issue are shown in a list that was printed in Scoutpost-Information January 1986 (the club journal for ArGe Pfadfinder, the German Scout stamp club). All these perfins are made by private companies, and most are initials of the company name. Most of them are recorded on the 6c stamp, some on the 1 1/2c and 12 1/2c stamps.
The "S" perfin was used by the Haagsche Kioskonderneming from 1913-1954. This is a bookstore located at railway stations, and is a common perfin. All three 1937 WJ stamps are known to have this perfin.
The "A.B." perfin was used by the N.V. Chemicalienhandel v/h Firma A. Bisschop Pzoon from 1929-1958. This is a chemical plant. Only the 6c stamp was perfin.
Thanks to Hallvard Slettebø, Tony Manson and William Baekers
ArGe Pfadfinder: Scoutpost "Information", January 1986
Catalogus van de perfins van Nederland en OG