Tài liệu tham khảo WikiPedia: Thú_biển //books.google.com/books?id=2rkHQpToi9sC&pg=PAfron... http://www.ucmp.berkeley.edu/mammal/mesaxonia/desm... http://www.noaa.gov/resource-collections/marine-ma... http://marinebio.org/oceans/marine-mammals/ http://www.marinemammalcenter.org/what-we-do/ http://www.marinemammalscience.org/ http://www.marinemammalscience.org/wp-content/uplo... //www.worldcat.org/oclc/316226747
