García-Chávez, A., Ramírez Chávez, E., & Molina-Torres, J. (2004). The genus Heliopsis (Heliantheae; Asteraceae) in Mexico and the alkamides stored in its roots. Instituto de Ecología, A.C.
Chicago-viite (17. p.)García-Chávez, Abraham, Enrique Ramírez Chávez, ja Jorge Molina-Torres. The Genus Heliopsis (Heliantheae; Asteraceae) in Mexico and the Alkamides Stored in Its Roots. Instituto de Ecología, A.C, 2004.
MLA-viite (9. p.)García-Chávez, Abraham, et al. The Genus Heliopsis (Heliantheae; Asteraceae) in Mexico and the Alkamides Stored in Its Roots. Instituto de Ecología, A.C, 2004.