@article{ghp17,
title = {Adaptive {IGAFEM} with optimal convergence rates: {H}ierarchical {B}-splines},
author = {Gantner, Gregor and Haberlik, Daniel and Praetorius, Dirk},
journal = {Math. Models Methods Appl. Sci.},
volume = {27},
number = {14},
pages = {2631--2674},
year = {2017},
doi = {10.1142/S0218202517500543},
eprint = {arXiv:1701.07764 }}