Root Vegetables: New Uses for Old Crops—Wanda W. Collins
Andean Tuber Crops: Worldwide Potential—Calvin R. Sperling and Steven R. King
Neglected Crops: 1492 from a Different Perspective—J.E. Hernándo Bermejo and J. León (eds.)
Outside links
Ulluco can be found in Lost Crops of the Incas from National Academy Press