Polyphase Sorting With Overlapped Rewind*
A variation of the polyphase merge technique
of sorting is described which permits one tape 
at a time to be rewound while the merge is continued on
the remaining tapes.  The result is the overlapping 
of a major portion of the rewind time.  The technique
should be considered whenever a sort is written 
to operate on five or more tapes that cannot be read backwards.
 The savings of the overlap method appear 
to increase as the number of available tapes is increased.
CACM March, 1964
McAlester, R. L.
