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» 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.    http://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.    http://www.cis.upenn.edu/~KeyKOS/

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

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