Dyfyniad APA

Van Duyn J. (1975). practical system and procedures manual. Reston publishing co.

Dyfyniad Arddull Chicago

Van Duyn J. Practical System and Procedures Manual. Virginia: Reston publishing co, 1975.

Dyfyniad MLA

Van Duyn J. Practical System and Procedures Manual. Reston publishing co, 1975.

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