Perhaps you should try some spelling variations:
peterov » petrov (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search), petru (Expand Search), petro (Expand Search)
petruoi » peteruoi (Expand Search), petriuoi (Expand Search), petruuoi (Expand Search), petrui (Expand Search), petroi (Expand Search)
peters » peter (Expand Search), petersen (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 ((peterov OR petruv) OR (((petr OR ((petruo OR peteruo) OR peters)) OR petruoi) OR per)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((peterov OR petruv) OR (((petr OR ((petruo OR peteruo) OR peters)) OR petruoi) OR per)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((peterov OR petruv) OR (((petr OR ((petruo OR peteruo) OR peters)) OR petruoi) OR per)) o.s.*.