Perhaps you should try some spelling variations:
petr » petro (Expand Search), per (Expand Search)
petroa » petrooa (Expand Search), peroa (Expand Search), petro (Expand Search), petrov (Expand Search), petra (Expand Search)
petru » petrou (Expand Search), peru (Expand Search), pentru (Expand Search)
petrou » petroou (Expand Search), perou (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petroou » petrooou (Expand Search), peroou (Expand Search)
petri » petroi (Expand Search), peri (Expand Search)
peterv » peters (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 ((((petr OR petroa) OR peterv) OR ((petru OR petrou) OR petroou)) OR (peter OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petr OR petroa) OR peterv) OR ((petru OR petrou) OR petroou)) OR (peter OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petr OR petroa) OR peterv) OR ((petru OR petrou) OR petroou)) OR (peter OR petri)) o.s.*.