Berry, Frances Stokes, and William D. Berry. 1999. "Innovation and diffusion models in policy research." In Paul A. Sabatier, ed., Theories of the Policy Process. Boulder, CO: Westview Press, pp. 169-200.

Blomquist, William. 1999. "The policy process and large-n comparative studies." In Paul A. Sabatier, ed., Theories of the Policy Process. Boulder, CO: Westview Press, pp. 169-200.

Clucas, Richard A. 2003. "Improving the Harvest of State Legislative Research." State Politics and Policy Quarterly 3:387-419.

Jewell, Malcolm E. 1982. "The Neglected World of State Politics." Journal of Politics 44:638-57.

Miller, Edwin Alan. 2004. "Advancing comparative state policy research: Toward conceptual integration and methodological expansion." State and Local Government Review, 36:35-58.

Sharkansky, Ira, and Richard I. Hofferbert. 1969. "Dimensions of state politcs, economics, and public policy." American Political Science Review, 63:867-79.

Walker, Jack L. 1969. "The diffusion of innovations among the American states." American Political Science Review, 63:880-99.