APA (7th ed.) Citation

Columbus, C., Roop, P., Roop, C., & Hanson, P. E. (1990). I, Columbus: My journal, 1492-3. Walker and Co..

Chicago Style (17th ed.) Citation

Columbus, Christopher, Peter Roop, Connie Roop, and Peter E. Hanson. I, Columbus: My Journal, 1492-3. New York: Walker and Co., 1990.

MLA (8th ed.) Citation

Columbus, Christopher, et al. I, Columbus: My Journal, 1492-3. Walker and Co., 1990.

Warning: These citations may not always be 100% accurate.