Hilgert, Joachim, and K.H. Hofmann. “On Sophus Lie’s Fundamental Theorem.” J. Funct. Anal. 67 (1986): 1–27.

Hilgert, Joachim, K.H. Hofmann, and J.D. Lawson. “Controllabilty of Systems on Nilpotent Lie Groups.” Beiträge Alg. Geom. 20 (1985): 185–90.

Hilgert, Joachim, and K.H. Hofmann. “Semigroups in Lie Groups, Semialgebras in Lie Algebras.” Trans. AMS 288 (1985): 481–504.

Hilgert, Joachim, and K.H. Hofmann. “Lorentzian Cones in Real Lie Algebras.” Monatshefte Math. 100 (1985): 183–210.

Hilgert, Joachim, and K.H. Hofmann. “Lie Semialgebras Are Real Phenomena.” Math. Ann. 270 (1985): 97–103.

Hilgert, Joachim, and K.H. Hofmann. “Old and New on SL(2).” Manuscripta Math. 54 (1985): 17–52.

Hilgert, Joachim, and K.H. Hofmann. “Lie Theory of Semigroups.” Semigroup Forum 30 (1984): 243–51.