Perhaps you should try some spelling variations:
petriv » petri (Expand Search), petrov (Expand Search), petriiv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petris » petri (Expand Search), petriis (Expand Search), petruis (Expand Search), petrois (Expand Search)
petroi » petri (Expand Search), petro (Expand Search), petrov (Expand Search), petrioi (Expand Search), petruoi (Expand Search), petrooi (Expand Search)
petruuv » petriuuv (Expand Search), petruuuv (Expand Search), petrouuv (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (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 ((((petriv OR petris) OR petroi) OR petruuv) OR ((petr OR peter) OR (peterov OR petruuv))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriv OR petris) OR petroi) OR petruuv) OR ((petr OR peter) OR (peterov OR petruuv))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriv OR petris) OR petroi) OR petruuv) OR ((petr OR peter) OR (peterov OR petruuv))) o.s.*.