Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petroi » petro (Expand Search), petrov (Expand Search), petrow (Expand Search), petruoi (Expand Search), petrooi (Expand Search), peroi (Expand Search)
petruooi » petruuooi (Expand Search), petrouooi (Expand Search), peruooi (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petrou » petruou (Expand Search), petroou (Expand Search), perou (Expand Search), petru (Expand Search), petro (Expand Search), 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 ((peruov OR petriov) OR ((petroi OR petruooi) OR (((petr OR petri) OR petrou) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((peruov OR petriov) OR ((petroi OR petruooi) OR (((petr OR petri) OR petrou) OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((peruov OR petriov) OR ((petroi OR petruooi) OR (((petr OR petri) OR petrou) OR peter))) o.s.*.