Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petrv » petrov (Expand Search), petri (Expand Search), petro (Expand Search), petriv (Expand Search), perv (Expand Search)
petrouv » petrov (Expand Search), petriouv (Expand Search), petroouv (Expand Search), perouv (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), peru (Expand Search), pentru (Expand Search), petri (Expand Search)
petroou » petrioou (Expand Search), petrooou (Expand Search), peroou (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 (((petrv OR petrouv) OR petr) OR petriov)) OR ((petru OR petroou) OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR (((petrv OR petrouv) OR petr) OR petriov)) OR ((petru OR petroou) OR peter)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR (((petrv OR petrouv) OR petr) OR petriov)) OR ((petru OR petroou) OR peter)) o.s.*.