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Alvarado Hernández, Alfredo 1945-, Gustavo Andoval, Pedro J. Argel M., Jorge Evelio Benavides, Óscar Brenes, Dale O. Evans, and Lawrence T. Szott. Nitrogen Fixing Trees for Acid Soils: Proceedings of a Workshop Sponsored By the Nitrogen Fixing Tree Association and the Centro Agronómico Tropical De Investigación Y Enseñanza July 3-8, 1994 Turrialba, Costa Rica. Arkansas, USA: Nitrogen Fixing Tree Association, 1995.

Alvarado Hernández, Alfredo 1945-, et al. Nitrogen Fixing Trees for Acid Soils: Proceedings of a Workshop Sponsored By the Nitrogen Fixing Tree Association and the Centro Agronómico Tropical De Investigación Y Enseñanza July 3-8, 1994 Turrialba, Costa Rica. Arkansas, USA: Nitrogen Fixing Tree Association, 1995.