Linda Kirschke has published a really interesting article on semi-presidentialism in sub-Saharan Africa. It appears in Comparative Political Studies, Vol. 40, No. 11, November 2007, pp. 1372-1394. She argues that power-sharing is difficult in neo-patrimonial systems and that semi-presidentialism is not well-suited to countries with such systems. Evidence from Burundi, Congo-Brazzaville and Niger supports the argument, which is backed up by a broader study as well.
Singapore is often overlooked as a case of semi-presidentialism, but a recent article throws light on the context in which the system was introduced in 1991 as well as the experience of the most recent presidential election. It is written by Li-ann Thio and appears in International Journal of Constitutional Law, Vol. 5, No. 3, 2007, pp. 526-543.
Further to the recent posting about Cindy Skach’s book, she has also published a couple of articles outlining her argument. They can be found in International Journal of Constitutional Law, Vol. 5, No. 1, 2007, pp. 93-121, and in Constitutional Political Economy, Vol. 16, No. 4, December 2005, pp. 347-368.