^Asimov, Isaac. Frontiers: New Discoveries About Man and His Planet, Outer Space, and the Universe. Dutton Adult. March 29, 1990. ISBN 0525246622.
^Asimov, Isaac. The Incredible Shrinking Planet. The Magazine of Fantasy and Science Fiction. March 1987: 118–128.
^ 4.04.1Asimov, Isaac. The Relativity of Wrong. 1988: 121. ...my own suggestion is that everything from Mercury up be called a major planet; everything from Ceres down be called a minor planet; and everything between Mercury and Ceres be called a "mesoplanet" (from a Greek word for "intermediate"). At the moment, Pluto is the only mesoplanet known.