Travers, Jeffrey; Milgram, Stanley (1969). "An Experimental Study of the Small World Problem". Sociometry. 32 (4): 425–443. doi:10.2307/2786545. JSTOR2786545.
Schnettler, Sebastian (2009). "A small world on feet of clay? A comparison of empirical small-world studies against best-practice criteria". Social Networks. 31 (3): 179–189. doi:10.1016/j.socnet.2008.12.005.
Schnettler, Sebastian (2009). "A structured overview of 50 years of small-world research". Social Networks. 31 (3): 165–178. doi:10.1016/j.socnet.2008.12.004.
Travers, Jeffrey; Milgram, Stanley (1969). "An Experimental Study of the Small World Problem". Sociometry. 32 (4): 425–443. doi:10.2307/2786545. JSTOR2786545.