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Will Luton: Free-to-Play: Making Money From Games You Give Away, s. 8. (F2P SUCCESS) ptgmedia.pearsoncmg.com: New Riders, 2013. ISBN 978-0-321-9190 Teoksen verkkoversio (pdf) (viitattu 12.12.2014). (englanniksi)
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Esko Vankka: Free-to-Play Games: Professionals' Perceptions (pdf) (s. 4) University of TampereSchool of Information SciencesInternet and Game StudiesMaster‟s Thesis. 2014. tampub.uta.fi. Viitattu 12.12.2014. (englanniksi)