Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petroov » petrov (Expand Search), petrioov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petru » pentru (Expand Search), petri (Expand Search), petriu (Expand Search), petrou (Expand Search), peru (Expand Search)
petriiv » petriiiv (Expand Search), petroiiv (Expand Search), periiv (Expand Search)
petriuo » petriiuo (Expand Search), petroiuo (Expand Search), periuo (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (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 ((((petriov OR petroov) OR petriiv) OR petru) OR ((perio OR petriuo) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriov OR petroov) OR petriiv) OR petru) OR ((perio OR petriuo) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriov OR petroov) OR petriiv) OR petru) OR ((perio OR petriuo) OR (petr OR peter))) o.s.*.