1. Beitrage zur entwicklung des psysiognomie-und mimikerkennes;Ahrens;Z. f. Exp. u. angew. Psychol.,1954
2. The development of the smiling response in early infancy;Ambrose,1961
3. Development of eye contact and facial scanning in infants;Bergman,1971
4. Eye contact as a setting event for infant learning;Bloom;Journal of Experimental Child Psychology,1974
5. Communicative rules and the sequential structure of infant behavior during normal and depressed interaction;Cohn,1982