C. Tickle

Local application of retinoic acid to the limb bond mimics the action of the polarizing region

L. Wolpert, L. Wolpert, B. Alberts, 1982, Nature.

Expression of the homeobox Hox-4 genes and the specification of position in chick wing development

L. Wolpert, L. Wolpert, C. Tickle, 1991, Nature.

Positional signalling and specification of digits in chick limb morphogenesis

D. Summerbell, L. Wolpert, L. Wolpert, 1975, Nature.