The new issue of Illustration magazine has a special feature on the life and career of Walt Reed, author of Illustrator in America, 1860-2000 and Harvey Dunn: Illustrator and Painter of the Pioneer West . He's also the founder of Illustration House, a gallery of illustration originals in New York.
An earlier version of Walt's book on the history of illustration was what first got me interested in the field of illustration when I was still in grade school. He later became involved with the Famous Artists Course. Those were the art instruction books that really formed my self-education, when I found a set from 1954 that included the instruction from Norman Rockwell, Al Parker, and Al Dorne.
The current issue of Illustration also has a terrific feature on Joseph Szokoli (1913-1981), who painted covers for many of the western, romance, and detective pulp magazines.
Here's more information:
Illustration Magazine official website
Illustrator in America, 1860-2000
Harvey Dunn: Illustrator and Painter of the Pioneer West
Famous Artists Course
Illustration House gallery