Clinical Chemistry 26(6), 724–729 (1980), DOI 10.1093/clinchem/26.6.724. Primary abstract and publisher byline verify initial-only G N Bowers Jr; no fuller identity inferred. Abstract reports 18380 ± 90 L mol^-1 cm^-1 at 401 nm and 25 °C for 35 micromol/L 4-nitrophenol in 10 mmol/L NaOH, and motivates matrix-specific calibration. Publisher academic.oup.com/clinchem/article-abstract/26/6/724/5727240 .