Classification of groups generated by 3-state automata over a 2-letter   alphabet
  This article contains most of the known results on the classification of groups generated by 3-state automata over a 2-letter alphabet, extending the previous papers 0704.3876 and math/0612178. 
Ievgen Bondarenko, Rostislav Grigorchuk, Rostyslav Kravchenko, Yevgen   Muntyan, Volodymyr Nekrashevych, Dmytro Savchuk, Zor...