@Article{trivers-1971a,
  author         = {R. Trivers},
  title          = {The Evolution of Reciprocal Altruism},
  year           = {1971},
  volume         = {46},
  pages          = {35--57},
  read-status    = {read},
  journal        = {Quarterly Review of Biology},
  key            = {trivers-1971a}
}