J. H. Stern y Stern, A.,
«Water harvesting through sand dams»,
Echo development notes (EDN), p. ca 17 p. : 8 fig., 2011.
J. H. Stern y Stern, A.,
«Water harvesting through sand dams». ECHO, Educational Concerns for Hunger Organization, North Ft. Myers, FL, USA, p. 20 p. : 9 fig., 2011.