[1] A blog item on the Viridis (and related) matplotlib color
scales is at http://bids.github.io/colormap/.
[2] Light, A., and P. J. Bartlein, 2004. The End of the Rainbow? Color
Schemes for Improved Data Graphics. Eos Trans. AGU, 85(40),
doi:10.1029/2004EO400002.
[3] Martin Jakobsson, Ron Macnab, and Members of the Editorial Board, IBCAO.
Selective comparisons of GEBCO (1979) and IBCAO (2000) maps.
https://www.ngdc.noaa.gov/mgg/bathymetry/arctic/ibcao_gebco_comp.html.
[4] Stephenson, David B., 2005. Comment on ``Color schemes for improved data
graphics,'' by A. Light and P. J. Bartlein. Eos Trans. AGU, 86(20).