Klausen (2007). "Pretend companions (imaginary playmates): The emergence of a field". The Journal of Genetic Psychology. 167 (4): 349-364. doi:10.3200/gntp.167.4.349-364. PMID17645227.
Klausen (2007). "Pretend companions (imaginary playmates): The emergence of a field". The Journal of Genetic Psychology. 167 (4): 349-364. doi:10.3200/gntp.167.4.349-364. PMID17645227.