Meriam, James L., author
John Wiley & Sons, 1975
Buku Teks
Alexander, Jeffrey C., author
Polity Press, 2017
Buku Teks
Jarvela, Sanna, author
Elsiever, 2011
Buku Teks
International Association of Gerontology; edited by Clark Tibbitts and Wilma Donahue
Columbia University Press, 1962
Buku Teks
Gennep, Arnold Van
The University of Chicago Press, 1975
Buku Teks