Cita APA (7a ed.)

Clemmer, G. (2010). The GIS 20 essential skills. ESRI Press.

Cita Chicago Style (17a ed.)

Clemmer, Gina. The GIS 20 Essential Skills. Redlands, California: ESRI Press, 2010.

Cita MLA (9a ed.)

Clemmer, Gina. The GIS 20 Essential Skills. ESRI Press, 2010.