God's Love "Made Visible". Eine Weihnachtsmusik von Dave Brubeck
H. Schroeter-Wittke, Der Evangelische Erzieher 41 (1989) 506–508.

Compactly Embedded Cartan Algebras and Invariant Cones in Lie Algebras
J. Hilgert, K.H. Hofmann, Advances Math. 75 (1989) 168–201.

A Note on Howe's Oscillator Semigroup
J. Hilgert, Ann. Inst. Fourier 39 (1989) 663–688.

Lie Groups, Convex Cones, and Semigroups
J. Hilgert, K.H. Hofmann, J.D. Lawson, eds., Lie Groups, Convex Cones, and Semigroups, Oxford University Press, Oxford, 1989.