I also found this puberty book that I bought that is pretty good. It is called The Boys Guide to Growing Up by Terri Couwenhoven, M.S.

I saw a book called
What's Happening to Tom
by Kate Reynolds
The cover looks like a book I made for my son using google images. I made a simple book using Microsoft word and images showing my son as a little toddler and then as a teen. I then put pictures of an image of progression from a baby to a man. I included information on hair growth, shaving, deodorant use, voice change and erections. It took about an hour to do with simple sentences, but you could just print out photos and talk about it together. I have another book somewhere in my house that came recommended but was too high of a level for my son, but may work for you. I will try to locate it. And give you the title.