How Do You Tuck In a Superhero?: And Other Delightful Mysteries of Raising Boys by Rachel Balducci, mother of five boys and one little girl: 'A field guide, a memoir, a mystery, and a love letter all in one.' Here is her blog http://testosterhome.net/about #Books #Boys
Great book for young adolescent girls...just the facts without being scary. It's part of the American Girl library but DON'T let them take it to school because it is cartoonishly graphic. Probably available at most bookstores, I got ours at Books A Million.