Memorandum Book Showing Colored Sketches Mostly of European Helmets

A book page with two sketches of helmets. The top sketch shows a side-view of a light brown helmet. The helmet has a curved top that covers the head and a faceplate with rectangular ventilation holes. There are two straps under the chin. The bottom sketch shows a side-view of a blue-grey helmet. The helmet covers the head and has a faceplate. There are two bolts on the faceplate. The background of the book is beige. There are handwritten notes on both sides of the two sketches. A small metal object is visible at the bottom.