Perhaps you should try some spelling variations:
petriv » petris (Expand Search), petrov (Expand Search), peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petroi » petro (Expand Search), petrov (Expand Search), petrow (Expand Search), peteroi (Expand Search), petruoi (Expand Search), petrooi (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petriov » peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), petrov (Expand Search)
petruv » peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search), petru (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 (((petriv OR petri) OR petroi) OR (petr OR ((petriov OR petruv) OR (petriv OR petri)))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriv OR petri) OR petroi) OR (petr OR ((petriov OR petruv) OR (petriv OR petri)))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriv OR petri) OR petroi) OR (petr OR ((petriov OR petruv) OR (petriv OR petri)))) o.s.*.