erd - How to show composite keys in Chen E-R Diagram -

how show composite keys in chen e-r diagram? have not used notation , don't it. references suffice, have excellent understanding of data modeling concepts (what brag!). note: aware of symbol associative entity, in such symbol, 1 may have auto-increment key pk, again, 1 may use 2 fks. in later case, pk composite. don't know how show since chen attribute symbol oval each attribute. thanks.

you can underline text of each attribute involved in primary key:

note associative entity set has composite key. introducing surrogate key changes regular entity set own identity. associative entity sets relationships subjects of further relationships, , relationships identified entity keys of related entity sets.