The files

- `include/Spectra/LinAlg/TridiagEigen.h`
- `include/Spectra/LinAlg/UpperHessenbergEigen.h`
- `include/Spectra/LinAlg/UpperHessenbergSchur.h`

were adapted from

- `Eigen/src/Eigenvaleus/SelfAdjointEigenSolver.h`
- `Eigen/src/Eigenvaleus/EigenSolver.h`
- `Eigen/src/Eigenvaleus/ComplexEigenSolver.h`
- `Eigen/src/Eigenvaleus/RealSchur.h`

in the [Eigen](https://eigen.tuxfamily.org/) library.

The authors for these code files are Gael Guennebaud (<gael.guennebaud@inria.fr>)
and Jitse Niesen (<jitse@maths.leeds.ac.uk>).

The file `include/contrib/LOBPCGSolver.h` was originally contributed by
Anna Araslanova (<araslanova.anna.a@gmail.com>).

The Jacobi-Davidson solvers were written by Felipe Zapata, Nicolas Renaud, Victor Azizi, Pablo Lopez-Tarifa
and Jens Wehner from the Netherlands eScience Center (<J.Wehner@esciencecenter.nl>).

The [Catch2](https://github.com/catchorg/Catch2) library was included for unit testing.
The authors are Phil Nash (<github@philnash.me>), Martin Hořeňovský (<martin.horenovsky@gmail.com>),
and Chris Thrasher (<https://github.com/ChrisThrasher>).

The [CPM.cmake](https://github.com/cpm-cmake/CPM.cmake) library was included for
CMake package management. The authors are listed in the
[contributors page](https://github.com/cpm-cmake/CPM.cmake/blob/master/CONTRIBUTORS.md).

Other part of Spectra was written by Yixuan Qiu (<yixuan.qiu@cos.name>).
