APA

Thompson C. E., Gibson J. N. A., . (2002). 50 foot challenges. Edimburg: Churchill Livingstone.

Chicago

Thompson Colin E, Gibson J N Alastair, . 2002. 50 foot challenges. Edimburg: Churchill Livingstone.

Harvard

Thompson C. E., Gibson J. N. A., . (2002). 50 foot challenges. Edimburg: Churchill Livingstone.

MLA

Thompson Colin E, Gibson J N Alastair, . 50 foot challenges. Edimburg: Churchill Livingstone. 2002.