O.Henry is one of the most famous American writers because "The Gift of the Magi"（賢者の贈り物） is used as English text in many junior high school in Japan.
By the way, I studied O.Henry's "The Exact Science of Matrimony" on the VOA Special English program several days ago. But, unfortunately, I could not understand the important part of the story so well.
So, I decided to buy the O.Henry's book translated in Japanese. I ordered its second hand book through "amazon". Finally, I understood the story after reading it.