widyantoro, A. et al.(2008).Effective Communication An Integrated Course of English for Vocational High School .Jakarta:Pusat perbukuan,Departemen Pendidikan Nasional.
Gaya MLA
widyantoro, A. et al..Effective Communication An Integrated Course of English for Vocational High School.Jakarta:Pusat perbukuan,Departemen Pendidikan Nasional,2008.Text.