Perhaps you should try some spelling variations:
peri » petri (Expand Search), per (Expand Search)
petruov » peteruov (Expand Search), petriuov (Expand Search), petruuov (Expand Search)
petroov » peteroov (Expand Search), petrioov (Expand Search), petruoov (Expand Search)
petruiu » peteruiu (Expand Search), petriuiu (Expand Search), petruuiu (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search)
petrui » peterui (Expand Search), petriui (Expand Search), petruui (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 ((petruov OR petroov) OR (petruiu OR ((petruo OR (petrui OR peri)) OR petr))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruov OR petroov) OR (petruiu OR ((petruo OR (petrui OR peri)) OR petr))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruov OR petroov) OR (petruiu OR ((petruo OR (petrui OR peri)) OR petr))) o.s.*.