If you want to see more fun how-to instruction (or stripey socks!), check out CollegiateShag.com - on the Photos page, Morgan has Arthur Murray's Shag and Big Apple instructions from the 1938 edition. Totally bummed that this info was removed by 1942!
(And since I mentioned Morgan, did you all see his AWESOME Super Mario dance routine that went viral this summer? He danced with one of my besties, Emily, and I lost my voice for a week from cheering for them!)