?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=Musnar+Indar&rft.aulast=Daulay&rft.au=Daulay%2C+Musnar+Indar&rft.title=Developing+the+Social+Science-History+Teaching+Materials+for+the+Sixth+Grade+Middle+School+Students&rft.date=2019&rft.genre=proceeding