Purbowo, Gallant, Mashuri -, and Putriaji Hendikawati. “KEEFEKTIFAN PEMBELAJARAN SNOWBALL THROWING BERBANTUAN LEMBAR KEGIATAN SISWA”. Unnes Journal of Mathematics Education 1, no. 1 (June 30, 2012). Accessed August 6, 2020. https://journal.unnes.ac.id/sju/index.php/ujme/article/view/256.