Question: Which artist did Neil Young cover, in his thirty-fourth studio album, that has been referred to as Canada's greatest songwriter? 
Sentence (from "Gordon Lightfoot"): Gordon Meredith Lightfoot Jr. {'1': ", '2': ", '3': ", '4': "} (born November 17, 1938) is a Canadian singer-songwriter who achieved international success in folk, folk-rock, and country music, and has been credited for helping define the folk-pop sound of the 1960s and 1970s.
Relevant evidence: No