How to get the GL code of materials??

Hi

i am trying to get the GL codes of the materials present in invoices, vendor and customer invoices. I read in the forum that there is not definite link between the material and GL codes. but its with the valuation class. I would like to know the table which has the GL codes for the valuation classes from where i could get the codes.

I tried the t-code OMWB which shows the GL codes for the material movements, but i am unable to find the table which has the link.

can anyone pls tell me which table i should lookup in order to get the GL codes for the valuation class.

Regards,

Sujai