The Intractability of Resolution. - Armin Haken (Theor. Comput. Sci., 1985)

Steepest Descent Can Take Exponential Time for Symmetric Connection Networks. - Armin Haken; Michael Luby (Complex Syst., 1988)

Counting Bottlenecks to Show Monotone P <=> NP. - Armin Haken (FOCS, 1995)

An Exponential Lower Bound for the Size of Monotone Real Circuits. - Armin Haken; Stephen A. Cook (J. Comput. Syst. Sci., 1999)