NIRMALA, B. “PENINGKATAN HASIL BELAJAR SAINS MELALUI SCIENCE PROCESS SKILLS APPROACH”. Jurnal Pendidikan Usia Dini, Vol. 8, no. 2, Nov. 2014, pp. 231 -40, http://103.8.12.212:33180/unj/index.php/jpud/article/view/3584.