Analisis effective tax rate dan book tax difference berdasarkan sektor industri (studi empiris perusahaan yang terdaftar di BEI periode 2009-2011 = The analysis of effective tax rate and book tax difference based on industry sector (empirical study at indonesia stock exchange listed companies period 2009 - 2011) (Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2013)