How to add sources and citations from records not available on FamilySearch
I have a question about a specific kind of source. I received a copy of the family tree of a great-aunt who gave it to my father many years ago. Unfortunately, I learned about the existence of this family tree after my father and great-aunt's passing, so I am not able to ask them specific questions about the author of this work. My great-aunt didn't have children.
This family tree was written on the typewriter in 1986, it is provided with sources from a parish register of a small town in the north-east of Italy, not available on FamilySearch. This work has the name of the author.
Knowing the importance of citations, how can I give credit to the author and properly cite these sources, even though they are not available on books or websites?
Any suggestions will be appreciated.
Thank you kindly,