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^Institute for the Comparative Study of Political Systems. Panama: election factbook, May 12, 1968. Washington: Institute for the Comparative Study of Political Systems. 1968. Pp. 10.
^Elections in the Americas : a data handbook / ed. by Dieter Nohlen, Vol. 1. [Oxford] [u.a.]: Oxford Univ. Press, 2005. Pp.532.
^Elections in the Americas : a data handbook / ed. by Dieter Nohlen, Vol. 1. [Oxford] [u.a.] : Oxford Univ. Press, 2005. Pp.529.