Epoxidation for dienes I have been asked to determine the major product for the reaction:

From the reagent given, one can tell that this is an epoxidation reaction. But, as only one mole of the peroxyacid is given, epoxidation can only take place in one of the two bonds.
How do you determine on which double bond the epoxidation will take place?
MCPBA preferentially reacts at the more electron-rich alkene, in this case the more substituted alkene according to this entry on chemistryportal.net here and this review RSC Advances