Susan-- A useful definition of a serial from the 2nd edition of the
Anglo-American Cataloguing Rules (1978) is: "A publication in any
medium issued in successive parts bearing numerical or chronological
designations and intended to be continued indefinitely.  Serials
include periodicals; newspapers; annuals (reports, yearbooks,etc.);
the journals, memoirs, proceedings, transactions, etc., of societies;
and numbered monographic series." p. 570
--Ted Rauch
--Columbia University