In writing this book, I have contacted many people out of the blue, asking them for help. I have been immensely touched by the generosity with which they have responded, spent time on my requests, and imparted their knowledge. I am in debt to the following for their kindness:
Chris Black, David Brewer, Richard Crampton, István Deák, Vesselin Dimitrov, Penelope Evans, James Felak, Aaron Fichtelberg, Ivaylo Gatev, Milan Grba, David Jacobs, László Karsai, Lasse Lehtinen, Radomír Malý, Takis Nitis, Hannu Rautkallio, Filip Reyntjens, Urmi Shah, Phil Taylor, Kjetil Tronvoll, Ilya Vlassov, James Ward.