On the Instanton Contributions to the Masses and Couplings of $E_6$
Singlets
Berglund, P
Candelas, P
de la Ossa, X
Derrick, E
Distler, J
Hubsch, T
Nucl.Phys.B454:127-163,1995
(26 May 1995)
doi:10.1016/0550-3213(95)00403-F
Singlets