Sören Bartels, Carsten Carstensen. Averaging techniques yield reliable a posteriori finite element error control for obstacle problems. Numerische Mathematik, 99(2):225-249, 2004. [doi]
@article{BartelsC04,
title = {Averaging techniques yield reliable a posteriori finite element error control for obstacle problems},
author = {Sören Bartels and Carsten Carstensen},
year = {2004},
doi = {10.1007/s00211-004-0553-6},
url = {http://dx.doi.org/10.1007/s00211-004-0553-6},
researchr = {https://researchr.org/publication/BartelsC04},
cites = {0},
citedby = {0},
journal = {Numerische Mathematik},
volume = {99},
number = {2},
pages = {225-249},
}