Wade-Giles is used very, very widely in English-language historical writing. Particularly anything that is more than about twenty years old. So you have to kn

Wade-Giles is used very, very widely in English-language historical writing. Particularly anything that is more than about twenty years old. So you have to know what the names of people and places are in both Pinyin and Wade-Giles, and often enough in whatever less-standard romanization the author happened to use.