Underwood–Miller(1993)ISBN 978-0887331770,第56–59頁 MickWall《The truth behind the Led Zeppelin legend》《泰晤士報》(2011-07-29),第15–16頁 MickWall《The truth behind the Led Zeppelin
ISBN 9781412926379 . Wallis, Mick; Shepherd, Simon, Studying plays, London: Arnold: 214, 1998, ISBN 0340731567 . "The Fourth Wall and the Third Space" by John