Utomo, Agung Priyo. “KAJIAN TENTANG PENGARUH TWO STAGE CLUSTER SAMPLING TERHADAP STATISTIK UJI-F”. Jurnal Matematika Sains Dan Teknologi, vol. 8, no. 2, Aug. 2007, pp. 89-97, http://jurnal.ut.ac.id/index.php/jmst/article/view/625.