Primary scan pmc.ncbi.nlm.nih.gov/articles/PMC283100/ . PNAS66(3),651–656(1970), DOI10.1073/pnas.66.3.651. Original PubMed byline G.E.Davies and G.R.Stark. Abstract: bifunctional reagent cross-links oligomer subunits; detergent gel electrophoresis resolves integral multiples of protomer mass, with reactivity differences for mixed protomers.