Cacioppo and Hawkley, “Loneliness”; Leary, Kelly, et al., “Construct Validity”; Gooding, Winston, et al., “Individual Differences in Hedonic Experience.”

Nichols and Webster, “Single-Item Need to Belong Scale”; Gardner, Pickett, et al., “On the Outside Looking In”; Kanai, Bahrami, et al.,“Brain Structure Links Loneliness”; Beekman, Stock, and Marcus, “Need to Belong, Not Rejection Sensitivity.”