APA

Puerto Rico, . (1977). Annual report. San Juan, P. R: Publishing Resources Inc.

Chicago

Puerto Rico, . 1977. Annual report. San Juan, P. R: Publishing Resources Inc.

Harvard

Puerto Rico, . (1977). Annual report. San Juan, P. R: Publishing Resources Inc.

MLA

Puerto Rico, . Annual report. San Juan, P. R: Publishing Resources Inc. 1977.