that are applicable. These are technical tools for evaluating sources and separating 'genuine' sources or content from forgeries or manipulation. External criteria involve issues relating to establishing authorship of a source or range of sources. It involves things like if an author wrote something themselves, if other sources attribute authorship to the source, agreement of independent manuscript copies on the content of a source.

Internal criteria involve formalities, style, and language for an author; if a source varies from the environment