Fernández-Suárez, Lucía, A. Gómez-Tato, J. Strom, and D. Tanré, The Lusternik-Schnirelmann category of Sp(3), Proc. AMS, 132(2):587-595, 2003.

Kahl, Thomas, On the algebraic approximation of Lusternik-Schnirelmann category, Journal of Pure and Appl. Algebra, 181:227-277, 2003.