@conference {romor2020pamm, title = {Multi-fidelity data fusion for the approximation of scalar functions with low intrinsic dimensionality through active subspaces}, booktitle = {Proceedings in Applied Mathematics \& Mechanics}, volume = {20}, number = {S1}, year = {2021}, publisher = {Wiley Online Library}, organization = {Wiley Online Library}, doi = {10.1002/pamm.202000349}, author = {Francesco Romor and Marco Tezzele and Gianluigi Rozza} }