APA

Hill T., . (1979). The watercolor painter's problem book. New York: Watson-Guptill Publications.

Chicago

Hill Tom, . 1979. The watercolor painter's problem book. New York: Watson-Guptill Publications.

Harvard

Hill T., . (1979). The watercolor painter's problem book. New York: Watson-Guptill Publications.

MLA

Hill Tom, . The watercolor painter's problem book. New York: Watson-Guptill Publications. 1979.