Thanks!
I think I'll do both just in case to be certain, since to me certified copy implies that they would need originals and beside there is no use of translated military book for me in future.
Here comes extract from email:
"This refers to your application for permanent residence in Canada. We are missing the following information and/or documentation in your application:
· a complete certified copy of your military book (Vojna Knjizica) with certified translation of the complete book into either English or French
. medical examination for yourself and your accompanying dependants
You will receive separate auto e-mail from us with the instructions
Unless originals are required, you are encouraged to scan and forward us the documents by email to vienn-visa @ international.gc.ca. Please ensure that attached documents are no bigger than 5 MB. Should you be unable to provide the requested documents by email or should originals be required, please send them by mail at the address identified below.
Please note that these documents must be provided to us within 60 days of the date on this letter. All documents not in English or French must be accompanied by a certified English or French translation."