Asymmetric Non-Abelian Orbifolds and Model Building
  The rules for the free fermionic string model construction are extended to include general non-abelian orbifold constructions that go beyond the real fermionic approach. This generalization is also applied to the asymmetric orbifold rules recently introduced. These non-abelian orbifold rules are quite easy to use. Examples are given to illustrate their applications. 
Zurab Kakushadze, Gary Shiu, and S.-H. Henry Tye