Ensiklopedi ilmu - ilmu sosial Jilid 1 - 2

 Kuper, Adam; Kuper, Jessica; Haris Munandar;

Jakarta : RajaGrafindo Persada , 2008

Quantitative and statistical research methods : from hypothesis to results

 Martin, William E.; Bridgmon, Krista D.,;

United State of America : Graffiti Pers , 2012