Koller, Marvin R
Random House, 1968
Buku Teks
edited by Chris Phillipson and Dale Dannefer
SAGE Publications, 2010
Buku Teks
Quadagno, Jill S., author
McGraw-Hill, 2002
Buku Teks
International Association of Gerontology; edited by Clark Tibbitts and Wilma Donahue
Columbia University Press, 1962
Buku Teks SO
Robert H. Binstock, Linda K. George, editor
Elsevier , 2011
Buku Teks