Perhaps you should try some spelling variations:
perv » per (Expand Search)
peru » petru (Expand Search), per (Expand Search)
petrv » peterv (Expand Search), petriv (Expand Search), petruv (Expand Search)
petriv » peteriv (Expand Search), petriiv (Expand Search), petruiv (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petruoi (Expand Search)
petriiio » peteriiio (Expand Search), petriiiio (Expand Search), petruiiio (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 ((peterov OR ((petrv OR perv) OR petriv)) OR (((petroi OR peru) OR petriiio) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((peterov OR ((petrv OR perv) OR petriv)) OR (((petroi OR peru) OR petriiio) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((peterov OR ((petrv OR perv) OR petriv)) OR (((petroi OR peru) OR petriiio) OR petr)) o.s.*.