Companion, Audrey L.
McGraw-Hill, 1979
Buku Teks
edited by Ronald J. Kendall
CRC Press, Taylor & Francis Group, 2008
Buku Teks
The National Association of Biology Teachers, 1970
Buku Teks
Hougen, Olaf A., author
John Wiley & Sons, 1943
Buku Teks
Artikel Jurnal