Books to help parents teach and kids learn the normal stages of puberty, when it should start, and when puberty would be considered early or late in boys and girls. Although many of these books are written for children as young as 8 or 9 years, when some begins start puberty, you may want to either read them first so you will be ready to answer any questions they bring up from your kids.
'Answers to Questions Boys Find Hard to Ask' about puberty, what's normal, and all of the changes they are going through. This book is written at a reading level for boys ages 9 through 12 (the age at which most boys start puberty).
'A Growing Up Guide for Parents and Daughters', this book is a complete guide to everything you and your daughter need to know about puberty, periods, etc.
'A Growing Up Guide for Parents and Sons' with everything you and your son wants to know about boys and puberty.
'Everything You Don't Want to Ask (But Need to Know)' about menstruation and puberty.
An illustrated guide to the 'mental and physical changes that take place during puberty.'
'A Survival Guide to Growing Up' for girls.
'A What's Happening to My Body? Book for Younger Girls'
'All About Adolescence and You'
...'but Were Afraid They'd Ask: The Secrets to Surviving Your Child's Sexual Development from Birth to the Teens' is a great book for parents to read before their kids start puberty and you have 'the talk'.
A great parenting book from the American Academy of Pediatrics that talks about puberty and many other 'teen' topics.