Jan Berenstain, co-creator of the beloved children's series, The Berenstain Bears, died Friday at the age of 88. Jan and her husband Stan published their first book — The Big Honey Hunt — in 1962. The series grew to more than 300 books and sold more than 250 million copies worldwide. Audie Cornish speaks with the couple's son, illustrator Mike Berenstain, who continued working on the books with his mother until her death last week.