You might try, if you can find them:
D. Daube, _The Sudden in the Scriptures_ (Leiden: E. J. Brill, 1964).
E. J. Pryke, _Redactional Style in the Markan Gospel: A Study of
Syntax and Vocabulary as Guides to Redaction in Mark_ (Cambridge:
C.U.P., 1978), pp. 87-96.
There is some discussion of the issue in relation to Luke's usage in
my _Goulder and the Gospels_, Chapter 6 (Promptitude and Alacrity).
All the best
Mark
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Dr Mark Goodacre M.S.Goodacre@bham.ac.uk
Dept. of Theology, University of Birmingham
Homepage: http://www.bham.ac.uk/theology/goodacre.htm