The collection of jew's harp notations.
There are jew's harp players who collect stamps and badges with images of jew's harps. There are people who collect instruments themselves. My personal passion is ways of recording of jew's harp music. There are a lot of them till the current moment and my collection renews constantly :)
Wolf Janscha notation system for the Jew's harp.
Nikolay Beerstov notation system for the Yakut Khomus
Roy Smeck notation system for the Jew's harp, USA
Vladimir Konchev notation, Altay
Tradotional notation system also can be used for the Jew's harp. Bela Bartok's score of doromb folk melody
There is the book I unfortunatele don't have yet.