Losada H, Pealing R, Cortés J and Vieyra J 1997:
The keeping of poultry and pigs in the backyards of the urbanised areas of Iztapalapa (east of Mexico City) as a proposal for sustainable production.
Livestock Research for Rural Development. Volume 9, Article #28.
Retrieved
, from http://www.lrrd.org/lrrd9/3/mex932.htm