Yichus as a selling point for a book, but at times, used selectively 1914 צוואת דוד/כתר ראש

It is now familiar practice for authors to tout on the title pages of their book their lineage, often in larger font than their own names, to a point where it can be hard to discern who the actual author is.

In 1914, Rabbi Shlomo Yehuda Leib Hacohen Ashkenazi published 2 works printed in 1 volume, צוואת דוד containing the will of his father, and כתר ראש which contains stories of the Vilna Gaon heard from R. Chaim of Volozhin. Interestingly, the author states different parts of his lineage in the 2 works he published, for the צוואת דוד he states he is a descendant of the Chacham Tzvi, and in the book on the Vilna Gaon he states he is a descendant of the Vilna Gaon. Presumably this was done to appeal to family members of both branches, each for the book that would relate to them.