get billing number from material document

Hi All:

         We are facing a probelm in a developed report.

         In our new report, we are going to get the billing number using material document of PGI (movement 601), but it seems there is no table can cover this. In VBFA, if we have invoice cancel and reverse PGI, developer don't know which material document mapping to which invoice.

         Please share idea, thanks.

Stephen