Tài liệu tham khảo WikiPedia: Độ_Richter http://www.britannica.com/EBchecked/topic/502877 http://aleph.nkp.cz/F/?func=find-c&local_base=aut&... http://www.iris.edu/seismon/ http://id.loc.gov/authorities/subjects/sh200200463... http://d-nb.info/gnd/7576375-8 https://www.youtube.com/watch?v=YXMKSOsv3QA https://web.archive.org/web/20160504144754/http://...
