(en) Patrick Fisher et Michael Taylor, « Do Red and Blue Make Green? An Analysis of the League of Conservation Voters Congressional Scorecards », Journal of Political Science, vol. 34, no 1, (ISSN0098-4612, lire en ligne, consulté le )
(en) Patrick Fisher et Michael Taylor, « Do Red and Blue Make Green? An Analysis of the League of Conservation Voters Congressional Scorecards », Journal of Political Science, vol. 34, no 1, (ISSN0098-4612, lire en ligne, consulté le )