Before revision: Gilbert J. Garraghan and Jean Delanglez A Guide to Historical Method p. 174, 1946 Prevenier, Walter(2001).
After revision: These are technical tools for evaluating sources and separating 'genuine' sources or content from forgeries or manipulation.Howell, MarthaGilbert J. Garraghan and Jean Delanglez A Guide to Historical Method p. 174, 1946 Prevenier, Walter(2001).