Bhadrachalam Chitturi William Fahle Z. Meng Linda Morales C. O. Shields Jr. Ivan Hal Sudborough Walter Voit An (18/11)n upper bound for sorting by prefix reversals. 3372-3390 2009 410 Theor. Comput. Sci. 36 http://dx.doi.org/10.1016/j.tcs.2008.04.045 db/journals/tcs/tcs410.html#ChitturiFMMSSV09