@article{Berry1998,
author = {Berry, W.D. and Ringquist, E.J. and Fording, R.C. and Hanson, R.L.},
title= {Measuring Citizen and Government Ideology in the American states, 1960–93},
year = {1998},
doi = {10.2307/2991759},
volume = {42},
number = {1},
pages = {327--348},
}