Mendoza, S. P. 1991. Sociophysiology of well-being in nonhuman primates. Laboratory Animal Science 41, 344-349.

We have found, for example, that formation of same-sex groups of squirrel monkeys is rarely accompanied by injurious aggression. Once unisexual groups have stabilized, formation of larger heterosexual groups generally proceeds smoothly (p. 347). [Group formation procedure is not described.] Generous amounts of vertical space and visual barriers seem to be effective in minimizing the frequency and severity of antagonistic encounters (p. 347).