When recommending tune/tab books for jamming, personally I think it's always a good idea the specify whether the book is intended for dulcimer-only jams ...where most all tunes are played in the key of D and most often in DAd tuning (with or without capos), and presented in dulcimer TAB form.
Many dulcimer players tend to congregate with other dulcimer players for club meetings and festival jamming....but we should keep in mind that in the music scene in general, jams typically include various instruments and jamming is in various keys.
There are many great jamming books out there- like the 'Fake book" series, or "Sing Out" for example. Those books are standard resources in folk jamming and can actually be used by people on various instruments, since they contain the simple melody in standard notation, the lyrics, and chord change indications of popular standard jamming songs, in the keys they might typically be played in by folk musicians.
It's always good to specify the format of the music in a music jam book, so one isn't surprised when it arrives in the mail and doesn't meet the intended need.

It's a great little drum for the money, very nicely made. It could also be used for non-tabor music situations and festivities as well.