Perhaps you should try some spelling variations:
petrov » petro (Expand Search), peterov (Expand Search), petruov (Expand Search), petroov (Expand Search)
petris » peteris (Expand Search), petruis (Expand Search), petrois (Expand Search)
petruois » peteruois (Expand Search), petruuois (Expand Search), petrouois (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
peteru » peter (Expand Search), petru (Expand Search), peters (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((petrov OR petrov) OR ((petris OR petruois) OR ((petr OR peteru) OR petri))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petrov OR petrov) OR ((petris OR petruois) OR ((petr OR peteru) OR petri))) o.s.*".