Perhaps you should try some spelling variations:
petriv » petrov (Expand Search), peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petroov » petrov (Expand Search), peteroov (Expand Search), petruoov (Expand Search), petrooov (Expand Search)
petris » peteris (Expand Search), petruis (Expand Search), petrois (Expand Search)
petrois » peterois (Expand Search), petruois (Expand Search), petroois (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petere » peter (Expand Search), peters (Expand Search), petre (Expand Search)
peteru » peter (Expand Search), petru (Expand Search), peters (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 (petroov OR petr)) OR (petere OR peteru)) OR petri) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriv OR (petris OR petrois)) OR (petroov OR petr)) OR (petere OR peteru)) OR petri) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriv OR (petris OR petrois)) OR (petroov OR petr)) OR (petere OR peteru)) OR petri) o.s.*.