|
|
|
|
|
|
Types of chemicals [CD-ROM]. (1999). World Book International Deluxe English Edition. California: World Book Inc. |
|
Chemistry for 'O` level. (1998). Singapore: Longman Singapore Publishers (Pte) Limited. |
|
Bullfrog [CD-ROM]. 1993-1998. Microsoft Encarta 99 Encyclopedia. United States of America: Microsoft Corporation. |
|
(1997). Illustrated Science Encyclopedia (Vol. 3) Raintree Steck-Vaughn. |
|
Building Acts to Cheatognatha. Funk & Wagnalls New Encyclopedia (Vol. 5). Funk & Wagnalls, Inc. (Publishers since 1876) |
|
[Online]. Available: http://www.purchon.co.uk/science/ph.html [1999, July 13] |
|
[Online]. Available: http://www.dnr.state.mn.us/fish_and_wildlife/frogs/frogs/bullfrog.html [1999, July 6] |
|
[Online]. Available: http://www.highlands.w-cook.k12.il.us/Prairie/AMPHIBIANS/Bullfrog%7F 1999, July 6] |
|
[Online]. Available: http://proto.wonderlab.org/olex/wetland/fdweb/organisms/text/Bullfrog.html [1999, July 6] |
|
|