During my weekend trip to Frankfurt, I only brought one copy of my book with me for
a couple of reasons. One reason is that most of the guests at the party are of an intellectual group armed with doctoral degree in Mathematics. I was not sure they would be interested in my book. However, to my surprise, I sold the only copy in my luggage and ran out of promotional postcards at the end of the trip (to be fair, it only happened at the last 15 minutes when I realized that either book sales NOW or never).