?url_ver=Z39.88-2004&rft_id=10.1016%2Fj.sna.2013.03.026&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=K.&rft.au=Ashraf%2C+K.&rft.aulast=Ashraf&rft.title=Sensors+and+Actuators%2C+A%3A+Physical&rft.atitle=Improved+energy+harvesting+from+low+frequency+vibrations+by+resonance+amplification+at+multiple+frequencies&rft.pages=123-132&rft.volume=195&rft.date=2013&rft.issn=09244247&rft.genre=article