Fixed BP paper ref.

Former-commit-id: ef5dec586c08ca10112623cbf3f01bec32d921bd

README.md

@@ -134,6 +134,6 @@ Discontinuous Galerkin Boltzmann (bns) solver [arXiv version](https://arxiv.org/
 
 Incompressible Navier-Stokes (discontinuous) Galerkin (ins) solver [publisher](https://doi.org/10.1016/j.jcp.2019.04.010), [arXiv version](https://arxiv.org/abs/1801.00246): `Karakus, A., Chalmers, N., Swirydowicz, K. and Warburton, T., 2017.A GPU accelerated discontinuous Galerkin incompressible flow solver, Journal of Computational Physics, Volume 390, Pages 380–404, 2019.`
 
-Optimization of elliptic mat-vec operations for (elliptic) solver on hexes [arXiv version](https://arxiv.org/abs/1711.00903): `Świrydowicz, K., Chalmers, N., Karakus, A. and Warburton, T., 2017. Acceleration of tensor-product operations for high-order finite element methods. arXiv preprint arXiv:1711.00903.`
+Optimization of elliptic mat-vec operations for (elliptic) solver on hexes [publisher](https://doi.org/10.1177/1094342018816368), [arXiv version](https://arxiv.org/abs/1711.00903): `Kasia Swirydowicz, Noel Chalmers, Ali Karakus, and T. Warburton, Acceleration of tensor-product operations for high-order finite element methods, The International Journal of High Performance Computing Applications, Vol 33, Issue 4, 2019.`