Juul, Svend, author
Texas StataCorp LP, 2014
Buku Teks
Juul, Svend, author
Stata Press, 2008
Buku Teks
Westview Press, 1980
Buku Teks
edited by Lorenz K. Y. Ng and Devra Lee Davis
Van Nostrand Reinhold, 1981
Buku Teks
Watts, Nancy T., author
Churchill Livingstone , 1990
Buku Teks