One of his happier finds was a map of Formosa created in 1940 by a famous cartographer. It was an extremely important find, for this was the very map that became the standard for subsequent cartography on Taiwan. Surprisingly, van der Aalsvoort found it tucked away, old and tattered, between the pages of a book. He said it was like running across a nugget of pure gold in a tossed salad.
如一張一九四○年製圖師凡博繪製、後來成為台灣地圖繪者基本藍圖的知名福爾摩沙地圖原稿，居然破舊地夾在一本目錄中，使他如沙粒中淘得金塊，興奮不已，並因出售者不明白地圖價值，而讓他以非常便宜的價錢購得。