DOCBOOK: How to change paper-size

[Lepekhine]

I want to change paper-type to A4.
I investigated mail-list archive and found the advice
to change print/dbparam.dsl file.
I use docbook-xsl-1.55.0.tar.gz and fop-0.20.4
No dsl files are in that kits.
Could you tell me where that dsl-file should be?
Thank you in advance.
Alexander