?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aulast=Braack&rft.aufirst=M&rft.au=Braack%2C+M&rft.issue=5&rft.issn=1064-8275&rft.date=6+September+2011&rft.title=SIAM+Journal+on+Scientific+Computing&rft.volume=33&rft.atitle=Duality+Based+A+Posteriori+Error+Estimation+for+Quasi-Periodic+Solutions+Using+Time+Averages&rft.pages=2199+-+2216&rft.genre=article