E_6 unification model building II. Clebsch-Gordan coefficients of   78$\otimes$78
  We have computed the Clebsch-Gordan coefficients for the product (000001) $\otimes$ (000001), where (000001) is the adjoint 78-dimensional representation of $E_6$. The results are presented for the dominant weights of the irreducible representations in this product. As a simple application we express the singlet operator in $ 27 \otimes 78 \otimes \bar{27}$ in terms of multiplets of the Standard Model gauge group. 
Gregory W. Anderson and Tomas Blazek