Elliot, John E
Goodtear, 1973
Buku Teks
Bronfenbrenner, Martin, author
Illinois, 1987
Buku Teks
Samuelson, Paul A. (Paul Anthony), 1915-2009, author
McGraw-Hill, 2010
Buku Teks
Taylor, John B., 1946-, author
South Western Cengage Learning, 2012
Buku Teks
Fairchild, Fred Rogers, author
Macmillan, 1940
Buku Teks