It is important to cite any maps you use in your research, no matter what the format or origin. You may find maps online, in books or atlases, or in journal articles, and the citation method will differ slightly. The resources below offer more information:
Maps produced by government agencies have different copyright policies than maps produced by private companies. The United Nations Policy on map use is an example of the types of restrictions placed on re-use of materials from the government or similar agencies without violating copyright laws.
Sometimes the use of maps can get a bit tricky and you may need to talk to an expert about copyright issues in regards to private or government maps. Please direct your questions to the U-M Library Copyright Office.