DAFTAR PUSTAKA
Harmoni,
Ati. 1996. Pengantar Ilmu Alamiah Dasar (IAD). Depok: Universitas Gunadarma
http://santrinitas.wordpress.com/kelas-x/sistem-periodik-unsur/
http://kemashsn.blogspot.com/2013/03/pengenalan-unsur-dan-sistem-periodik.html
http://budisma.web.id/materi/sma/fisika-kelas-xi/pengertian-energi/
http://tugas2tuton.blogspot.com/2011/11/tugas3-ilmu-alamiah-dasar_25.html http://iffahufairohpsikolog.blogspot.com/2012/05/pengukuran-besaran-dan-dimensi.html
http://labibahrukmana.blogspot.com/2012/05/tugas-3-iad.html