APA
Watt S. B., . (1976). 21 chain and washer pumps. London: Intermediate Technology Publictions Ltd.
Chicago
Watt S B, . 1976. 21 chain and washer pumps. London: Intermediate Technology Publictions Ltd.
Harvard
Watt S. B., . (1976). 21 chain and washer pumps. London: Intermediate Technology Publictions Ltd.
MLA
Watt S B, . 21 chain and washer pumps. London: Intermediate Technology Publictions Ltd. 1976.