What is the name of the childrens book series about historical characters growing up with imaginary friends?

When I was a child (late 1980s, early 1990s) I had a series of books about famous historical characters (Jackie Robinson, Sacagewa, Hellen Keller, etc.) who had imaginary friends that helped them overcome obstacles as they grew up. It was a great series, but now I can't remember the name or any of the authors (I believe they were not all written by the same person). I remember the book covers being tall, mostly white hardjackets, with a simple color illustration on the front. If anyone knows what I'm talking about and can help me out with a title, author or publishing company, I would really appreciate it. Now that I'm an adult, I'd like to find this series for my children.

What is the name of the childrens book series about historical characters growing up with imaginary friends?
"The Value Tales" includes stories about Hans Christian Andersen, Florence Nightingale, Captain Cook, Will Rogers, the Mayo Brothers, Marie Curie, and others


http://www.amazon.com/s/ref=nb_ss_b/104-...