APA

Ridout R. W. C., . (1973). Facts of English. : Pan American World Airways, New York.

Chicago

Ridout Ronald Witting Clifford, . 1973. Facts of English. : Pan American World Airways, New York.

Harvard

Ridout R. W. C., . (1973). Facts of English. : Pan American World Airways, New York.

MLA

Ridout Ronald Witting Clifford, . Facts of English. : Pan American World Airways, New York. 1973.