Perhaps you should try some spelling variations:
petriv » petris (Expand Search), petrov (Expand Search), peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petriiv » peteriiv (Expand Search), petruiiv (Expand Search), petroiiv (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petruuo » peteruuo (Expand Search), petruuuo (Expand Search), petrouuo (Expand Search)
petriuo » peteriuo (Expand Search), petruiuo (Expand Search), petroiuo (Expand Search)
petero » peter (Expand Search), peters (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 ((petriv OR petriiv) OR ((((petr OR petri) OR petero) OR (petruuo OR petriuo)) OR per)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriv OR petriiv) OR ((((petr OR petri) OR petero) OR (petruuo OR petriuo)) OR per)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriv OR petriiv) OR ((((petr OR petri) OR petero) OR (petruuo OR petriuo)) OR per)) o.s.*.