Mark C. Wilson, Journal of Algebra 175 (1995), 661-696.
Abstract: In recent papers J. Bergen and D.S. Passman have applied so-called `Delta methods’ to enveloping algebras of Lie superalgebras. This paper generalizes their results to the class of Lie colour algebras. The methods and results in this paper are very similar to those of Bergen and Passman, and many of their proofs generalize easily. However, at some points there are serious difficulties to overcome. The results obtained show that if $latex L$ is a Lie colour algebra then the join of all finite-dimensional ideals of $latex L$ controls certain properties of the universal enveloping algebras $latex U(L)$. Specifically, we consider primeness, semiprimeness, constants, semi-invariants, almost constants, faithfulness of the adjoint action, the centre, almost centralizers and the central closure.