Gaya APA

Christiansen, R, L. (1980). Monthly Report Volcanic and Seismic Activity At Mount St. Helens 1980 (April 1980). Washington: University of Washington.

Gaya MLA

Christiansen, R., L.. "Monthly Report Volcanic and Seismic Activity At Mount St. Helens 1980". April 1980 Washington: University of Washington, 1980. Text.