PBS
Pbs: American Experience: John Brown's Holy War: Pottawatomie Massacre
PBS provides information on John Brown's involvement in the Pottawatomie Massacre and the reasons behind the massacre.
Other
Kansas Cyclopedia of State History: Pottawatomie Massacre
Describes the Pottawatomie Massacre which was John Brown's plan to drive the pro-slavers out of the area. From a 1912 encyclopedia.