Simply a great reference book! Lots of illustrations with color plates, three-view drawings, technical specifications, performance data and a brief history of each aircraft. It is divided up into historical sections and covers virtually every nation that has build a helicopter, auto-gyro or VTOL aircraft. I use it for model building, model making and for our new model kit lines. The drawings are accurate and are a great source to confirm or dispute model kits and preparation for making them. I have yet to find a better source as this for helicopters and VTOL craft. Of the highest quality as only Italy can produce!