NASA
Nasa Space Science Data Archive: Comet Fact Sheet
This comet fact sheet, supplied by the NSSDC, provides a table of information on selected comets, complete with commentary when appropriate. Includes details of missions to observe these comets.
California Institute of Technology
Spitzer Science Center: Riding a Trail of Debris
This image, titled "Riding a Trail of Debris" features the comet Encke with a clearly visible tail comprised of "gravel-like debris." The text under the image details various specifics about the picture.