Harrison studied a multitude of English speaking poets including W.B. Yeats, Dylan Thomas, Robert Bly, and Robert Duncan. Harrison also cited a diverse set of influences from world poetry including: French Symbolist poetry; the Russian poets Georgy Ivanov and Vladimir Mayakovsky; the German poet Rainier Maria Rilke; and Chinese T'ang Dynasty poetry. He felt a particular affinity for the French poet Rene Char and the Russian poet Sergei Yesenin as they both came "from humble beginnings out in the country". Harrison's sequence of prose poems "Letters to Yesenin" (1973) was inspired by Yesenin.