A document visualization system includes an extraction unit (1) for processing a first medical record (11) in a collection of medical records (10). The medical records include text (13) in a natural language. The extraction unit extracts an indicator from the text (13), which indicator is indicative of a reference to medical records (21) in the collection of medical records (10). A visualization unit (2) generates a visual representation of the first medical record (11), a visual representation of the second medical record (21), and a visual representation of the reference. A control unit (3) controls the extraction unit (1) to process a plurality of medical records of the collection of medical records (10), to extract indicators from text of the medical records.