Ski property listing websites

Hey all, 

My father has a property he likes to rent out during the ski season (1 bed apartment in Borovets, Bulgaria) and he's given me the task of finding a few websites that he could advertise it on. However, I know nothing of the ski property listings world and so was wondering if anyone on here could so kind as to recommend a few sites that they've either used before or have heard good things about. 

My father used chaletsdirect & chaletfinder last year and wants to find sites that offer a similar service but for a fairer price. Would anybody know of any such sites? 

Also, I hope I've posted in the correct area of the forum, if not then I hope it isn't too much hassle for one of the mods will move this. 

Thanks 

Lee