T. GleasonT. R. SebancA. M. HartupW. Willard 2000 Imaginary Companions of pre School Children Developmental Psychology 36 4, July 2000
E. V. Hoff 2004–2005 A Friend Living Inside Me – The Forms and Functions of Imaginary Companions institutionLund University Sweden
E. HurlockM. Burstein 1932 The Imaginary Playmate: A questionnaire study