1. Seed size variation and predation of seeds produced by wild and crop–wild sunflowers
2. Asch, David L., and Nancy B. Asch 1978 The Economic Potential of Iva annua and its Prehistoric Importance in the Lower Illinois Valley. In The Nature and Status of Ethnobotany, edited by Richard I. Ford, pp. 300-341. Anthropological Papers No. 67, Museum of Anthropology, University of Michigan, Ann Arbor.
3. Asch, David L., and Nancy B. Asch 1985 Prehistoric Plant Cultivation in Western Illinois. In Prehistoric Food Production in Eastern North America, edited by Richard I. Ford, pp. 149-203. Anthropological Papers No. 75, Museum of Anthropology, University of Michigan, Ann Arbor.
4. Digital imaging analysis of size and shape of wheat and pea upon heating under anoxic conditions as a function of the temperature