Loopgraafmortier Duits model H20 (Leichter Minenwerfer n/A) kaliber 7,58 cm met getrokken loop, op grondplaat met radaffuit work of the Royal Engineers in the European war, 1914-19 / Royal Engineers Institute : Water supply : part I: general development of organization, plant … work of the Royal Engineers in the European war, 1914-19 / Royal Engineers Institute : Bridging work of the Royal Engineers in the European war, 1914-19 / Royal Engineers Institute. Secretary : Supply of engineer stores and equipment
