Anything by Maria Montessori, and try the website for Montessori Internationale for some interesting articles
Children:The Challenge by Rudolph Dreikurs
Positive Discipline by Jane Nelson
How Children Fail & How Children Learn by John Holt
Why Gender Matters by Leonard Sax
Endangered Minds by Jane Healy
The Elegant Universe by Brian Greene (Nova on PBS)
The Tipping Point, Blink, & Outliers by Malcolm Gladwell
Iron John & The Sibling Society by Robert Bly
Girlfighting by Lyn Mikel Brown
Cesar Milan’s coaching of people for assertiveness and leadership
Judith Martin
Ann Landers
Abigail Van Buren
some of Rabbi Schmuley’s work
goodatdoingthings.com