Airways of America: the United Air Lines
Airways of America: the United Air Lines; a geological and geographical description of the route from New York to Chicago and San Francisco
by A. K. Lobeck
Publisher: Port Washington, N.Y., Kennikat Press [1970]
ISBN: 0804613230
Natural wonders of America
(by the editors of American heritage. Editor in charge, Beverley da Costa. Introd. by Alvin M. Josephy, Jr; ISBN: 0070011559;
30% match)