Sorry that it took so long - that was quite a journey. I tought I could order the book via courier, but it was only for use in the reading room, which was still closed in February. So I tried to get it over interlibrarian loan, but ours has so much to do due to Covid, that they asked me to hold the request back. But then it came to my mind that it is a swiss book, so I could have a look at it after a meeting at the national library :-D.
Anyway: to be honest, it does not look very reliable to me for data prior to church books. It doesn't have a table of contents, it starts right away with text, then has several smaller family trees to pop up.
At the back it has some sort of listed (male?) index with lots of data (unsourced) and an index of women who married in that has abbreviations to link to their pop up family tree. The sources are less than one third of a page and names like "Stammtafel Schneeli", "Alemania" (which I think is a journal, but who knows what he meant or which issue of which year he used), or "Steuerbücher" (tax books).
If you wish, please PM me and I can send you the picture of the sources. I guess, most sources would be available at the Staatsarchiv Zürich, as I know some of them are traditional sources to get prior to the church books in Switzerland. Of course you can't always get a confident connection, depending on the information that you find (e.g. with some luck you might find a will or purchase contract, but how do you know for sure that Hans with his son Uli really is your ancestor and not his cousin?).
