just wikipedia mainly but I'm sure there are more out there. Propfans will offer huge fuel avings n the future if they get implemented. The biggest problem with them is cabin noise (blade tips go supersonic) and danger of a blade breaking and entering the cabin so they will probably be rear mounted. Passenger opinion is also quite low due to the wierd looking blades sticking out in all directions. Here are some articles about them or planes they ae associated with:
Propfan - Wikipedia, the free encyclopedia
McDonnell Douglas MD-94X - Wikipedia, the free encyclopedia
Antonov An-70 - Wikipedia, the free encyclopedia
Green sky thinking - carbon credits and the propfan comeback?-12/06/2007-Los Angeles-Flight International
easyJet.com - The ?easyJet ecoJet?: to cut CO2 emissions by 50% by 2015
and here is a picture of easyjets concept:
Google Image Result for http://gizmodo.com/assets/resources/2007/07/ecojet11.jpg
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