APA

Zelko H. P., .Successful conference and discussion techniques. New York: McGraw-Hill Book Company.

Chicago

Zelko Harold P, .Successful conference and discussion techniques. New York: McGraw-Hill Book Company.

Harvard

Zelko H. P., .Successful conference and discussion techniques. New York: McGraw-Hill Book Company.

MLA

Zelko Harold P, .New York: McGraw-Hill Book Company. .