@article{Olson1981,
author = {Olson, J.M.},
title= {Spectrally encoded two-variable maps},
year = {1981},
doi = {10.1111/j.1467-8306.1981.tb01352.x},
journal = {Annals of the Association of American Geographers},
volume = {71},
number = {2},
pages = {259--276},
}