Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petroiov (Expand Search)
petr » petri (Expand Search), petro (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), pentru (Expand Search), petri (Expand Search)
petroi » petrioi (Expand Search), petrooi (Expand Search), petri (Expand Search), petro (Expand Search), petrov (Expand Search)
petrou » petriou (Expand Search), petroou (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petriu » petriiu (Expand Search), petroiu (Expand Search), petri (Expand Search), petris (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 ((petr OR (per OR petru)) OR petroi)) OR (petrou OR (petriu OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR ((petr OR (per OR petru)) OR petroi)) OR (petrou OR (petriu OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR ((petr OR (per OR petru)) OR petroi)) OR (petrou OR (petriu OR peter))) o.s.*.