Rothuizen, J., Heirwegh, KPM., & Vankouwen, AM. (1988). Novel Method for High-performance Liquid-chromatography of Azo Derivatives of Conjugated and Unconjugated Bilirubin. Journal of Chromatography. Biomedical Applications, 427(1), 19-28. https://doi.org/10.1016/0378-4347(88)80101-4 (Original work published 1988)