Retrieved 2007-11-05., reprinted in McCaffery 1991, pp. 263–285 McCaffery 1991 Walker, Doug (September 14, 2006).
Ανακτήθηκε στις 2007-11-05. , reprinted in McCaffery 1991, σελίδες 263–285 McCaffery 1991 Walker, Doug (September 14, 2006).