Kuiper Belt and the Oort Cloud - Discusses the proposed vast cloud at the outer reaches of the solar system that comets reside in.
Oort Cloud & Sol b? - Briefly discusses Oort Could objects, including comets and brown dwarfs.
Views of the Solar System: The Oort Cloud - Introduction the immense spherical cloud surrounding the planetary system, considered the edge of the Sun's orb of physical, gravitational, or dynamical influence.
Wikipedia: Oort Cloud - Postulated spherical cloud of comets situated about 50,000 to 100,000 AU from the sun.
