The Decreasing Of Chromium (Cr) In Liquid Waste Of Process Equation in Leather Tanning Using Compound Alkali Ca(OH)2, NaOH, And NaHCO3 (Case Study in Pt Trimulyo Kencana Mas Semarang) - Joko, Tri (Magister Kesehatan Lingkungan UNDIP, 2003)