APA

Helenes J., De Guerra C., Vasquez J., De Guerra C. & Vasquez J.Palynology and chrosnostratigraphy of the upper cretaceous in the subsurface of the barinas area, western Venezuela. : .

Chicago

Helenes J, De Guerra C, Vasquez J, De Guerra C and Vasquez J.Palynology and chrosnostratigraphy of the upper cretaceous in the subsurface of the barinas area, western Venezuela. : .

Harvard

Helenes J., De Guerra C., Vasquez J., De Guerra C. and Vasquez J.Palynology and chrosnostratigraphy of the upper cretaceous in the subsurface of the barinas area, western Venezuela. : .

MLA

Helenes J, De Guerra C, Vasquez J, De Guerra C and Vasquez J.: . .