@article{10_2140_agt_2015_15_3025,
     author = {Balmer, Paul and Dell{\textquoteright}Ambrogio, Ivo and Sanders, Beren},
     title = {Restriction to finite-index subgroups as \'etale extensions in topology, {KK{\textendash}theory} and geometry},
     journal = {Algebraic and Geometric Topology},
     pages = {3023--3045},
     year = {2015},
     volume = {15},
     number = {5},
     doi = {10.2140/agt.2015.15.3025},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2015.15.3025/}
}