{"references": ["Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), A computationally compact representation of Magnetic-Apex and Quasi-Dipole coordinates with smooth base vectors, J. Geophys. Res., 115(A8), A08322, doi:10.1029/2010JA015326.", "Richmond, A. D. (1995), Ionospheric Electrodynamics Using Magnetic Apex Coordinates, Journal of geomagnetism and geoelectricity, 47(2), 191\u2013212, doi:10.5636/jgg.47.191."]}

When referencing this package, please cite both the package DOI and the Apex Coordinates journal article: Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), A computationally compact representation of Magnetic-Apex and Quasi-Dipole coordinates with smooth base vectors, J. Geophys. Res., 115(A8), A08322, doi:10.1029/2010JA015326.

Minor release to include IGRF13 coefficients, expands the type of allowed inputs into the subsol routine, fixes several bugs in edge cases, expands testing support to include Python 3.6-3.9, updates the documentation, and updates the continuous integration testing environments.