Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), petriuv (Expand Search), petruuv (Expand Search), petrouv (Expand Search)
petruo » petru (Expand Search), petro (Expand Search), petriuo (Expand Search), petruuo (Expand Search), petrouo (Expand Search)
petroi » petri (Expand Search), petro (Expand Search), petrov (Expand Search), petrioi (Expand Search), petruoi (Expand Search), petrooi (Expand Search)
petriuuv » petriiuuv (Expand Search), petruiuuv (Expand Search), petroiuuv (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (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 (petruv OR petruv)) OR (((petruo OR petroi) OR petriuuv) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR (petruv OR petruv)) OR (((petruo OR petroi) OR petriuuv) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR (petruv OR petruv)) OR (((petruo OR petroi) OR petriuuv) OR (petr OR peter))) o.s.*.