Cite

Trench map. St. Julien 28 N.W. 2 / Ordnance Survey.

MLA

Survey, Great Britain. Ordnance. Trench Map. St. Julien 28 N.W. 2 / Ordnance Survey. Ordnance Survey, 1917. https://collections.library.yale.edu/catalog/15237947.

APA, 6th edition

Survey, G. B. O. (1917). Trench map. St. Julien 28 N.W. 2 / Ordnance Survey. [Maps]. Ordnance Survey, https://collections.library.yale.edu/catalog/15237947.