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Lua i Stíl Chicago (17ú heag.)Hernandez, Hector M., agus Hector Godinez A. Contribution to the Knowledge of Threatened Mexican Cacti. Instituto de Ecología, A.C, 1994.
Lua MLA (9ú heag.)Hernandez, Hector M., agus Hector Godinez A. Contribution to the Knowledge of Threatened Mexican Cacti. Instituto de Ecología, A.C, 1994.