20.O27 [Cambrelin and Lille Wood, South of Nachtegaal and North of Bultehoek] December 26, 1917
Covers an area equivalent to square O27 on the corresponding WWI map sheet 20. Negative roll 9B, photo 209. Annotations on recto: north arrow pointing to the left. WWI Aerial Photograph Collection: Box 1, Envelope 68.