?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.aufirst=Umimartawati&rft.au=S+Tri%2C+Umimartawati&rft.aulast=S+Tri&rft.degree=S1&rft.date=2005&rft.inst=UNY&rft.title=Sistem+Pegas+Massa+dengan+Dua+Derajat+Kebebasan