Sisam, J. (1947). The use of aerial survey in forestry and agriculture (6th.). Imperial forestry bureau and pastures and field crops.

Sisam, J.W.B. The Use of Aerial Survey in Forestry and Agriculture. 6th. Aberystwyth: Imperial forestry bureau and pastures and field crops, 1947.

Sisam, J.W.B. The Use of Aerial Survey in Forestry and Agriculture. 6th. Imperial forestry bureau and pastures and field crops, 1947.