A Consistent Prescription for Combining Perturbative Calculations and   Parton Showers in Case of Associated Z b anti-b Hadroproduction
  This paper presents the method of combining parton shower formalism with perturbative calculations (matrix elements) in form of a Monte-Carlo algorithm for the process g g -> Z b anti-b,consistenlty including the heavy quark masses and overlap removal. 
B. P. Kersevan, I. Hinchliffe, L. Mijovic