Hello Arisko,
Collecting WWF stamps is a good idea and I believe it brings a lot of enjoyment because most of the stamps were issued in high quality and#1514; IMO, with spectacular designs.
The best online catalogue for WWF stamps was the web site of Groth AG from Switzerland, who also produced WWF items like FDC's and MC's, but unfortunately, he closed his shop and I can't find his site any more.
There is a catalogue for WWF. See here a copy of its cover:
https://viapontica.org/en/stamps-wi...-foundation/We have a thread about WWF stamps shows many sets. It is far to be complete list, but all WWF sets show primates and monkeys are shown (except one set), most times with maxicards:
https://goscf.com/t/79817In the first page of the above thread you can see a scan of Domfil WWF catalogue:
https://goscf.com/t/79817#723913 br /
Enjoy Philately! Happy Collecting!