BJÖRK LARS, ERIKSON UNO, INGELMAN BJÖRN, and ZAAR BIRGlTTA. 1974. “Improved Polymeric Contrast Agents for Roentgenologic Examination of the Gastrointestinal Tract: I. Preliminary Report on the Chemistry of the Polymers”. Upsala Journal of Medical Sciences 79 (2):103-5. https://doi.org/10.3109/03009737409178976.