Perhaps you should try some spelling variations:
petriv » petrov (Expand Search), petruiv (Expand Search), petroiv (Expand Search), periv (Expand Search)
peterov » petrov (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (Expand Search)
petrois » petruois (Expand Search), petroois (Expand Search), perois (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petruou » petruuou (Expand Search), petrouou (Expand Search), peruou (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (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 petrois)) OR peterov) OR petr) OR ((petruou OR peter) OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriv OR (petris OR petrois)) OR peterov) OR petr) OR ((petruou OR peter) OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriv OR (petris OR petrois)) OR peterov) OR petr) OR ((petruou OR peter) OR petri)) o.s.*.