Some well-known anarcho-communist writers are Peter Kropotkin, Ricardo Flores Magón and Nestor Makhno. Anarcho-communism is opposed to more authoritarian forms advocated by Leninists and Maoists. These groups have violently clashed in Russia, Korea and Spain over their beliefs. Some examples of anarcho-communism in practice include the Free Territory of Ukraine, Capitol Hill Autonomous Zone, Shinmin Autonomous Region, and the Revolutionary Spain.