Some topics are extremely important to have information on, but so sensitive and touchy that it is hard to get people to talk about them.
This is a good book to help with gathering information about sensitive characteristics in surveys.
Lots of math proofs to explain the techniques. Such as Item Count Technique and Three Card Method.
Chapter 4.6.2 is about Crossed Model for the case of two stigmatizing characteristics.
Chapter 7 is is on protection of privacy.
This is a good book. I look forward to digging into it and figuring out how to write computer programs for some of the techniques.