Crawford, Douglas M. (1964). "Our Agricultural Attachés". Farmer's World. Washington: U.S. Govt. Print. Off. Archived from the original on 2016-01-10. Retrieved 2010-08-23.
Crawford, Douglas M. (1964). "Our Agricultural Attachés". Farmer's World. Washington: U.S. Govt. Print. Off. Archived from the original on 2016-01-10. Retrieved 2010-08-23.