Perhaps you should try some spelling variations:
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petruv » peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search), petru (Expand Search), petrov (Expand Search)
petroov » peteroov (Expand Search), petruoov (Expand Search), petrooov (Expand Search), petrov (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
peteru » peter (Expand Search), petru (Expand Search), peters (Expand Search)
peterov » petrov (Expand Search)

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((((petr OR peteru) OR petruv) OR (peterov OR (petroov OR peterov))) OR (per OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petr OR peteru) OR petruv) OR (peterov OR (petroov OR peterov))) OR (per OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petr OR peteru) OR petruv) OR (peterov OR (petroov OR peterov))) OR (per OR petri)) o.s.*.