source document

Noun

 * 1) An original document that is subsequently copied, translated, or transcribed.
 * 2) An original document or record that provides proof of activity that is summarized elsewhere (e.g. case notes, medical chart, diary entry, minutes of a meeting, etc.).
 * 3)  A document that provides official notification of a credit or debit to an account, such as a bank statement, bill of sale, invoice, receipt, etc.

Translations

 * Dutch: verantwoordingsstuk,
 * Finnish: alkutosite
 * French: pièce justificative
 * Polish: dokument źródłowy