. p. 47. ISBN   1403965382 . http://books.google.co.uk/books?id=BZIY7TGKySsC&pg=PA47 . Retrieved 2011-04-10 .   ^ Mäyrä, Frans (2008). An Introduction to Games Studies: Games in Culture . SAGE . p. 104. ISBN   1412934451 . http://books.google.co.uk/books?id=iI0kAQAAIAAJ . Retrieved 2011-04-10 . "The gameplay of Doom is at its core familiar from the early classics like