Following Garraghan (in: A Guide to Historical Method, 168) puts six questions that should be answered as minimal standard for a sound historical method:
When was the source, written or unwritten, produced (date)?
Where was it produced (localization)?
By whom was it produced (authorship)?
From what pre-existing material was it produced (analysis)?
In what original form was it produced (integrity)?
What is the evidential value of its contents (credibility)?
References
Gilbert J. Garraghan, A Guide to Historical Method, Fordham University Press: New York (1946). ISBN0-8371-7132-6.
Louis Gottschalk, Understanding History: A Primer of Historical Method, Alfred A. Knopf: New York (1950). ISBN0-394-30215-X.
Martha Howell and Walter Prevenier, From Reliable Sources: An Introduction to Historical Methods, Cornell University Press: Ithaca (2001). ISBN0-8014-8560-6.
C. Behan McCullagh, Justifying Historical Descriptions, Cambridge University Press: New York (1984). ISBN0-521-31830-0.
R. J. Shafer, A Guide to Historical Method, The Dorsey Press: Illinois (1974). ISBN0-534-10825-3.