Παραπομπή σε μορφή APA (7η εκδ.)

Black, W. P. M. (1979). The strength of clay subgrades: Its measurement by a penetrometer. Pavement Design Division, Highways Dept., Transport and Road Research Laboratory.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Black, W. P. M. The Strength of Clay Subgrades: Its Measurement by a Penetrometer. Crowthorne, Berkshire: Pavement Design Division, Highways Dept., Transport and Road Research Laboratory, 1979.

Παραπομπή σε μορφή MLA (8th εκδ.)

Black, W. P. M. The Strength of Clay Subgrades: Its Measurement by a Penetrometer. Pavement Design Division, Highways Dept., Transport and Road Research Laboratory, 1979.