Perhaps you should try some spelling variations:
peri » petri (Expand Search), per (Expand Search)
petriv » peteriv (Expand Search), petriiv (Expand Search), petruiv (Expand Search)
petriiv » peteriiv (Expand Search), petriiiv (Expand Search), petruiiv (Expand Search)
petriu » peteriu (Expand Search), petriiu (Expand Search), petruiu (Expand Search)
petruuo » peteruuo (Expand Search), petriuuo (Expand Search), petruuuo (Expand Search)
petriiuo » peteriiuo (Expand Search), petriiiuo (Expand Search), petruiiuo (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (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 ((((petriu OR peri) OR petero) OR (petruuo OR petriiuo)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriv OR petriiv) OR ((((petriu OR peri) OR petero) OR (petruuo OR petriiuo)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriv OR petriiv) OR ((((petriu OR peri) OR petero) OR (petruuo OR petriiuo)) OR petr)) o.s.*.