López Camelo, Andrés F. (2004). Manual for the Preparation and Sale of Fruits and Vegetables. Food and Agriculture Organization of the United Nations. стр. 6. ISBN92-5-104991-2. Приступљено 2009-07-31. „However, in the case of potatoes (Figure 10), sweet potatoes, and other root vegetables, readiness for harvest is based on the percentage of tubers of a specific size.”