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