Perthel, Dirk, author
Amsterdam University, 1981
Buku Teks
World Health Organization
World Health Organization, 1995
Buku Teks
Tinbergen, Jan, 1903-, author
McGraw-Hill, 1967
Buku Teks
Griffin, Keith B., author
Addison-Wesley, 1970
Buku Teks
edited by Hal Hill
Allen & Unwin , 1994
Buku Teks