20.O35 [Carrefour Richelieu, Houthulst Forest] December 10, 1917
Covers an area equivalent to square O35 on the corresponding WWI map sheet 20. Negative roll number 9B, photo 147. Annotations on recto: north arrow pointing to the left with an "x" on the opposite edge of the photo. WWI Aerial Photograph Collection: Box 3, Envelope 28.