Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petriv » petrov (Expand Search), petruiv (Expand Search), petroiv (Expand Search), periv (Expand Search)
petero » peters (Expand Search), petro (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (Expand Search)
petr » petru (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 ((((peruov OR petriov) OR petriv) OR petri) OR ((petero OR petris) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((peruov OR petriov) OR petriv) OR petri) OR ((petero OR petris) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((peruov OR petriov) OR petriv) OR petri) OR ((petero OR petris) OR (petr OR peter))) o.s.*.