The earliest use of a random graph model was by [[Helen Hall Jennings]] and [[Jacob Moreno]] in 1938 where a "chance sociogram" (a directed Erdős-Rényi model) was considered in studying comparing the fraction of reciprocated links in their network data with the random model.<ref>{{cite journal |last1=Moreno |first1=Jacob L |last2=Jennings |first2=Helen Hall |title=Statistics of Social Configurations |journal=Sociometry |date=Jan 1938 |volume=1 |issue=3/4 |pages=342–374 |doi=10.2307/2785588|jstor=2785588 }}</ref> Another use, under the name "random net", was by Solomonoff and Rapoport in 1951, using a model of directed graphs with fixed out-degree and randomly chosen attachments to other vertices.<ref>{{cite journal |last1=Solomonoff |first1=Ray |last2=Rapopst |first2=Anatol |title=Connectivity of random nets |journal=Bulletin of Mathematical Biophysics |date=June 1951 |volume=13 |issue=2 |pages=107–117 |doi=10.1007/BF02478357}}</ref> | The earliest use of a random graph model was by [[Helen Hall Jennings]] and [[Jacob Moreno]] in 1938 where a "chance sociogram" (a directed Erdős-Rényi model) was considered in studying comparing the fraction of reciprocated links in their network data with the random model.<ref>{{cite journal |last1=Moreno |first1=Jacob L |last2=Jennings |first2=Helen Hall |title=Statistics of Social Configurations |journal=Sociometry |date=Jan 1938 |volume=1 |issue=3/4 |pages=342–374 |doi=10.2307/2785588|jstor=2785588 }}</ref> Another use, under the name "random net", was by Solomonoff and Rapoport in 1951, using a model of directed graphs with fixed out-degree and randomly chosen attachments to other vertices.<ref>{{cite journal |last1=Solomonoff |first1=Ray |last2=Rapopst |first2=Anatol |title=Connectivity of random nets |journal=Bulletin of Mathematical Biophysics |date=June 1951 |volume=13 |issue=2 |pages=107–117 |doi=10.1007/BF02478357}}</ref> |