APA

NORTHEN HELEN, . (1969). Social work with groups. New York: Columbia University Press.

Chicago

NORTHEN HELEN, . 1969. Social work with groups. New York: Columbia University Press.

Harvard

NORTHEN HELEN, . (1969). Social work with groups. New York: Columbia University Press.

MLA

NORTHEN HELEN, . Social work with groups. New York: Columbia University Press. 1969.