While working in the laboratory of Paul Doty at Harvard University, Marmur discovered that the denaturation of DNA was reversible (DNA hybridization) and depended on salt- and GC-content. Marmur and Doty accurately described the conditions for the optimal renaturation of DNA complementary strands, upon denaturation by high temperatures. They proposed that high temperature was required to block the formation of weak bonds between non-complementary strands and to guarantee the proper pairing of complementary molecules. With J. Eigner and C. Schildkraut. Digital facsimile from PubMedCentral at this link.
See also J. Marmur and D. Lane, "Strand separation and specific recombination in deoxyribonucleic acids: Biological studies," Proc. Nat. Acad. Sci (U.S.A.) 46, 453-461. Digital facsimile of that paper from PubMedCentral at this link.