Lyx: citation

[Jörg Kühne]

Dear Lyx user list

In Lyx appears the citation in form of (vgl. Scheer, 2002, S. 4) but in the PDF 
the citation appears in the form of [vgl. 1, S. 4]. What can I do to change the 
PDF citation view to (vgl. Scheer, 2002, S. 4)?

Best regards

Joerg