The quantity of references is not as important as the quality of references. Scholarly references from journals such as the Annals of the Association of American Geographers or Professional Geographer are far better than those such as Time or Newsweek . Encyclopedias are not a legitimate, collegiate source and should not be cited . National Geographic is not a great source either. Be careful about using Internet sources.
Any idiot can construct a web page and put what appears to be legitimate information on it.
Internet sources can be unreliable and surfing the web can be a colossal waste of time. The best source for information is data that you collected first hand or data collected by reputable researchers. The number of references needed in a paper depends on the topic. Generally, papers that argue some point need at least two, one for each side of an argument. This of course is the bare minimum in many cases.