1Landau, Elaine. Pluto: From Planet to Dwarf. New York, NY: Scholastic Inc., 2008.
2Rao, Joe. “Finding Pluto: Tough Task, Even 75 Years Later.” Space. March 11, 2005. Accessed: February 8, 2012.
3Sexton, Colleen A. Pluto. Minneapolis, MN: Bellwether Media, Inc., 2010.
4“Solar System Exploration: Pluto.” NASA. February 8, 2012. Accessed: February 20, 2012.
5“Solar System Exploration: Pluto vs. Earth.” NASA. February 8, 2012. Accessed: February 20, 2012.
6Than, Ker. “Pluto Is Now Just a Number: 134340.” USA Today. September 12, 2006. Accessed: February 8, 2012.
7Vogt, Gregory. Pluto and the Search for New Planets. New York, NY: Steadwell Books, 2001.
8Winrich, Ralph. Pluto: A Dwarf Planet. Mankato, MN: Capstone Press, 2008.