Ron van Maanen's list of ships

We really would like to know Ron van Maanen's sources so we can find the documents that he saw. The reason is that Ron usually omitted gun lists that I know were on certain documents (because I have copies of them). His list is a really tremendous work, and is extremely helpful. I find, though, that he makes some mistakes about ships, probably based on Vreudenhil's list. We also have information that he had not seen, mostly from the Wrangell Collection document and from S. Hart's papers from the Gemeentearchief Amsterdam. He also omits ships, such as that which seems to have been named Scheletje (24 guns and a crew of 70 men). His list seems to confirm that there were ships hired by the Directors in 1652 that were not part of the fifty funded by the Extraordinarie Equipage (50 hired by the Directors and 100 ships hired by the admiralties)