I found at all 54 men with surname Doruska in whole Czech republic - if you are searching for not common surnames in CR, you can use database on web pages of Home Department on www.mvcr.cz
- it's between statistics.
Another way how to get any info is to call to the municipal authorities and ask there if anyone remember someone called Doruska in that village or in near villages... the phone number is 00420619544222 - but there is problem with english - I'm affraid that there won't be anyone who will understand.. it's just a small village.. Or you can try to write a letter... the post address is
Obecni urad Merin
594 42 Merin
Czech republic. If you need any help, write me email on email@example.com