Perhaps you should try some spelling variations:
petruov » petrov (Expand Search), petriuov (Expand Search), petruuov (Expand Search), petrouov (Expand Search)
petroiv » petrov (Expand Search), petrioiv (Expand Search), petruoiv (Expand Search), petrooiv (Expand Search)
petrois » petris (Expand Search), petriois (Expand Search), petruois (Expand Search), petroois (Expand Search)
petriio » petriiio (Expand Search), petruiio (Expand Search), petroiio (Expand Search)
petruiou » petriuiou (Expand Search), petruuiou (Expand Search), petrouiou (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (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 ((petruov OR petroiv) OR (((petrois OR petriio) OR petruiou) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruov OR petroiv) OR (((petrois OR petriio) OR petruiou) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruov OR petroiv) OR (((petrois OR petriio) OR petruiou) OR (petr OR peter))) o.s.*.