Willis 2014, 219쪽, 'Progressive' music can be seen as an experimentation with alternative routes"; Moore 2004, 22쪽, "What was so revolutionary about this post-hippie music that came to be called 'progressive' ... was that ... the umbilical link between idiolect and style had been broken." 괄호 없는 하버드 인용 error: 대상 없음: CITEREFMoore2004 (help); Macan 1997, 246쪽, "the progressive rock of the 1970s had been 'progressive' only as long as it pushed the stylistic and conceptual boundaries of rock outwards" 괄호 없는 하버드 인용 error: 대상 없음: CITEREFMacan1997 (help)Willis, Paul E. (2014). 《Profane Culture》. Princeton University Press. ISBN978-1-4008-6514-7.
Willis 2014, 219쪽, 'Progressive' music can be seen as an experimentation with alternative routes"; Moore 2004, 22쪽, "What was so revolutionary about this post-hippie music that came to be called 'progressive' ... was that ... the umbilical link between idiolect and style had been broken." 괄호 없는 하버드 인용 error: 대상 없음: CITEREFMoore2004 (help); Macan 1997, 246쪽, "the progressive rock of the 1970s had been 'progressive' only as long as it pushed the stylistic and conceptual boundaries of rock outwards" 괄호 없는 하버드 인용 error: 대상 없음: CITEREFMacan1997 (help)Willis, Paul E. (2014). 《Profane Culture》. Princeton University Press. ISBN978-1-4008-6514-7.
