1. Theoretical approaches to loneliness;Perlman,1982
2. Characteristics of the 1st, 2nd, and 3rd child;Adler;Child,1928
3. The Psychology of Affiliation. Experimental Studies of the Sources of Gregariousness;Schachter,1959
4. The study of ordinal position: antecedents and outcomes;Sampson,1965
5. Birth order: a critical review;Adams;Sociometry,1972