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)
petroa » petro (Expand Search), petrov (Expand Search), petra (Expand Search), petrioa (Expand Search), petrooa (Expand Search), peroa (Expand Search)
petriou » petriiou (Expand Search), petroiou (Expand Search), periou (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 ((petru OR petroa) OR periv)) OR (petriou OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriov OR petroov) OR ((petru OR petroa) OR periv)) OR (petriou OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriov OR petroov) OR ((petru OR petroa) OR periv)) OR (petriou OR (petr OR peter))) o.s.*.