Fletcher, Colin.
The Man Who Walked Through Time
. New York: Random House, 1967. (Hiking in the Grand Canyon)
Huxley, Juliette.
Wild Lives of Africa
. New York: Harper and Row, 1963. (Personal experience in Africa’s game parks)
Weinstein, M. and J. Goodman.
Play Fair
. Impact Publishers, San Louis Obispo, CA. 1980. (Outdoor Activities)
Wolfe, Linnie Marsh.
Son of the Wilderness.
The Life of John Muir
. New York: Alfred A. Knopf, 1945. (biography)