Capability

Capability-Based Computer Systems - Henry M. Levy; Digital Press, 1984, ISBN 0932376223. Thorough survey and description of early capability and object based hardware and software systems. Out of print, available as free download, PDF format.
www.cs.washington.edu/homes/levy/capabook/

KeyKOS - Persistent, pure capability, nanokernel OS, for IBM S/370 mainframe systems, by Key Logic, Inc. Influenced design of other capability OSs, notably EROS and successors. Set of papers, notes, patents, bibliography.
www.cis.upenn.edu/~KeyKOS/

Wikipedia: Capability-based Addressing - Encyclopedia article, with links to many related topics.
en.wikipedia.org/wiki/Capability-based_addressing

Wikipedia: Capability-based Security - Encyclopedia article, with links to many related topics.
en.wikipedia.org/wiki/Capability-based_security