APA
Walker H. M. 1., . (1934). Mathematics essential for elementary statistics: a self-teaching manual. New York: Henry Holt.
Chicago
Walker Helen Mary 1891, . 1934. Mathematics essential for elementary statistics: a self-teaching manual. New York: Henry Holt.
Harvard
Walker H. M. 1., . (1934). Mathematics essential for elementary statistics: a self-teaching manual. New York: Henry Holt.
MLA
Walker Helen Mary 1891, . Mathematics essential for elementary statistics: a self-teaching manual. New York: Henry Holt. 1934.