Abstract: A document microfilming system for information retrieval is provided having photographic apparatus for recording of series of documents on microfilm and identifier indicia printing means for applying an identifying number to the documents or sets of documents. The photographic apparatus comprises means auxiliary to that forming images of the documents on the film strip for forming a designator image on the film strip in adjacent, proximate relationship to images of selected documents. The identifier indicia imprinting means applies an identifying number to each primary document and also applies the same number to all sub-documents associated with that primary document.