Harrer wrote some of the earliest books in the modern age (published in the 1950s) of mountaineering. The White Spider deals with his ascent of the titular White Spider, a near vertical challenge in the Alps that prepared him to pioneer several important climbs in the Himalayas. It’s an interesting look into the equipment, comradeship and ethics of the early climbers.
Of course, his most famous book, Seven Years in Tibet, covers his years in Tibet (1944-1951) after escaping from a World War II prisoner of war camp in India (Harrer was in the German army). This book is noteworthy because of its account of the last days of a free Tibet (China invaded in 1950). It was made into a movie starring Brad Pitt.