http://www.themathpage.com/aprecalc/logarithms.htm Logarithms - Topics in precalculus Logarithms - Topics in precalculus http://www.themathpage.com/aprecalc/logarithms.htm#laws Logarithms - Topics in precalculus - TheMathPage themathpage.com Logarithms - Topics in precalculus - TheMathPage themathpage.com Logarithms - Topics in precalculus Logarithms - Topics in precalculus - TheMathPage The Math Page; Logaritmos; Lawrence Spector [em inglês]