The Artist’s guide to sketching

In the early 1980's, a couple of fresh-faced art students Thomas Kinkade ("The Painter of Light") and James Gurney (Dinotopia) found themselves working as background artists on the Ralph Bakshi/Frank Frazetta sword & sorcery film Fire and Ice. They had met in 1976 as freshman college roommates. Before they became established in their careers, they "sketched their way across America" as art hobos, hopping freight cars, finding adventure, and drawing, drawing, drawing. Much of this attitude and some of this biography made its way into the book, The Artist's Guide to Sketching -- a book firmly committed to the idea that artists need to get outdoors -- into the real world -- and draw from life.
This is not a traditional "how to" book. The authors place a lot of emphasis on using the environment to capture mood and say that the sketching artist must allow his feelings and impressions to show themselves in the finished work. Sketching isn't rendering. It is expressing feelings.