I'm not talking about crying scenes in books but bills that have crying at least in part,  as subject matter.

There's  one called crying. Really original title. .about the role crying plays in life. . The roles it has played in various cultures, how crying was viewed in different periods in history. The way it was used in literature at different points.  The emotional,  biological, and biochemical stuff about tears themselves. .... It can be pretty interesting.

There's another small one I found on Amazon called the path of tears.  It's written by a guy who asher decades of not crying slowly taught himself to cry again and sets aside dedicated times for crying in his life.  The way others will dedicate time to medidation. He feels it has changed his life and wrote this book to tell his story and then goes through step by step how top rekearn to cry if you struggle with it.  The description of the crying process in the how to chapter is tingling to read for a dacryphile. He goes through everything from preparing things to hold on to, prepping the space,  feeling it well up.... You can watch it play out in your head as you read.

There's others I haven't read yet. One about the wailing women of the  yemenite Jewish tradition any how and why they make  others cry. 
There's another one  about art moving people to tears. 

Any others anyone wants to recommend?