Why is Pluto not a Planet: http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/  

Pluto is a Planet, by John Stansberry: http://www.scienceclarified.com/dispute/Vol-1/Is-Pluto-a-planet.html 

 Is Pluto a giant comet? From the Harvard-Smithsonian Center for Astrophysics http://www.icq.eps.harvard.edu/ICQPluto.html 

 Having Pups Over Pluto and the Planetary Misfits of the Kuipers, by Robert Sanders for SPACEDAILY: http://www.spacedaily.com/news/outerplanets-03e.html 

Defining Ceres, Lowell Observatory: https://lowell.edu/sga/defining-ceres/ 

Pluto and Planethood Lowell Observatory: https://lowell.edu/pluto-at-85-pluto-and-planethood/  

Solar System: http://solarsystem.nasa.gov/planets/ 

It May Be Small, But It’s Still A Planet, from Space Today Online: http://www.spacetoday.org/SolSys/Pluto/PlutoPlanet.html 

A Good Definition of the Word “Planet”: Mission Impossible, by Gibor Basri, for the Universe in the Classroom, the Astronomical Society of the Pacific: http://www.astrosociety.org/education/publications/tnl/59/planetdefine.html 

The International Astronomical Union: http://www.iau.org/ 

Pluto and the Developing Landscape of Our Solar System: http://www.iau.org/public/themes/pluto/  

The International Astronomical Union definition of planets focus on the resolutions about half way down the page:   http://www.iau.org/news/pressreleases/detail/iau0602/  

‘New planet’ forces rethink, by Helen Briggs, BBC News Online: http://news.bbc.co.uk/2/hi/science/nature/3516952.stm 

 2004 NASA News Release: Most Distant Object in Solar System Discovered, http://www.jpl.nasa.gov/releases/2004/85.cfm 

Distant Object Could be ‘Tenth Planet’, by Maggie McKee for the New Scientist: http://www.newscientist.com/article.ns?id=dn4776 

http://www.gps.caltech.edu/~mbrown/sedna/index.html#planets 

http://www.gps.caltech.edu/~mbrown/planetlila/