@article{purcino_festin_elkan_2000, title={Identification of effective strains of Bradyrhizobium for Arachis pintoi}, volume={77}, number={4}, journal={Tropical Agriculture}, author={Purcino, H. M. A. and Festin, P. M. and Elkan, G. H.}, year={2000}, pages={226–231} }
 @book{elkan_2000, title={Microbial evolution: A narrative history of microbiology at North Carolina State University}, publisher={Raleigh, NC: Published by North Carolina Agricultural Foundation, Inc}, author={Elkan, G. H.}, year={2000} }
 @book{elkan_upchurch_1997, title={Current issues in symbiotic nitrogen fixation: Selected papers of the 15th North American Conference on Symbiotic Nitrogen Fixation held at North Carolina State University, Raleigh, NC, USA, 13-17 August 1995}, publisher={Dordrecht; London: Kluwer Academic}, author={Elkan, Gerald H. and Upchurch, R. G.}, year={1997} }
 @article{elkan_1992, title={TAXONOMY OF THE RHIZOBIA}, volume={38}, ISSN={["0008-4166"]}, DOI={10.1139/m92-075}, abstractNote={ Extensive cross testing on a relatively few legume hosts led initially to a taxonomic characterization of rhizobia based on bacteria–plant cross–inoculation groups. This has gradually become less acceptable, and has been replaced by taxonomic groupings derived from numerical taxonomy, carbohydrate metabolism, antibiotic susceptiblities, serology, and various molecular techniques. It has long been recognized that there are two distinct groups of rhizobia based on growth rate. The fast-growing genus Rhizobium includes R. leguminosarum, R. meliloti, R. loti, R. galegae, R. tropici, and R. huakuii. The slow-growing genus Bradyrhizobium contains only one recognized species, B. japonicum. Two new genera have been recognized: Azorhizobium, with one recognized species (A. caulinadans), and Sinorhizobium, with two species (S. fredii and S. xinjiangensis). Genetic studies of both the fast- and slow-growing groups show unacceptably wide intrageneric and intergeneric diversity. Although there have been some elegant studies of some of the genetic relationships among rhizobia, overall there has (have) not been the comprehensive study(ies) needed to allow a conclusive taxonomic scheme. Because proposals for revision are accelerating, minimum standards have been proposed by the International Subcommittee for the Taxonomy of Rhizobium and Agrobacterium. Key words: Rhizobium taxonomy, classification of rhizobia, interrelationships of rhizobia. }, number={6}, journal={CANADIAN JOURNAL OF MICROBIOLOGY}, author={ELKAN, GH}, year={1992}, month={Jun}, pages={446–450} }
 @inbook{elkan_bunn_1992, title={The Rhizobia}, ISBN={0387972587}, booktitle={The Prokaryotes : a handbook on the biology of bacteria : ecophysiology, isolation, identification, applications}, publisher={New York : Springer-Verlag}, author={Elkan, G. H. and Bunn, C. R.}, year={1992}, pages={2197} }
 @inbook{elkan_kuykendall_1982, title={Carbohydrate metabolism}, ISBN={9780198545552}, booktitle={Nitrogen fixation.Volume 2.Rhizobium}, publisher={Oxford: Clarendon Press}, author={Elkan, G. H. and Kuykendall, L. D.}, year={1982}, pages={147} }
 @article{elkan_1971, title={Biochemical and genetical aspects of the taxonomy of Rhizobium japonicum}, DOI={10.1007/bf02661842}, journal={Plant and Soil}, author={Elkan, G. H.}, year={1971}, pages={85} }