Breithaupt, Don & Breithaupt, Jeff: ”Logical Songs: Progressive Pop”, Night Moves. Pop Music in the Late ’70s. St. Martin’s Publishing Group, 2014. ISBN 978-1-46687138-0Google-kirjat (viitattu 2.9.2020). (englanniksi)
Roberts, Adam: Pink Floyd (Edited by John Clute and David Langford) The Encyclopedia of Science Fiction. päivitetty 28.6.2019. London: Reading: SFE Ltd: Ansible Editions. Viitattu 26.10.2020. (englanniksi)
