1. Colegio de PostgraduadosCP56230MontecillosEstado de MéxicoMéxico
2. CIMMYTApdo. Postal 6‐64106600México CityMéxico
3. USDA‐ARS and Dep. of AgronomyKansas State Univ.4011 Throckmorton HallManhattanKS66506
4. Institut National de la Recherche Agronomique, UR631 Station d'Amélioration Génétique des AnimauxBP 5262732326Castanet‐TFrance
5. Dep. of Epidemiology & BiostatisticsMichigan State Univ.909 Fee Road, Room B601East LansingMI48824