Non polarized capacitor in schematics
Thanks for the replies to my question.
I actually realized that I had not checked properly the documentation. I sorted out which kind of capacitors I needed by first looking at the board. If there is no plus sign (as in my case) I checked the part list. In may case the BP transistors where not listed as BP but only as Electrolytic capacitor (E.C.) but then looking finally at the schematics I saw that the capacitor is BP. Also the BP is written only on one channel I figured it out that of course the same capacitor on the other channel would be BP as well.
This is my first time that I try to restore an Audio Amplifier so I am more aware of what to do now  thanks to the replies that suggested me to look at the schematics. Thanks again for all the replies. Cheers