Perhaps you should try some spelling variations:
petris » petri (Expand Search), petriis (Expand Search), petruis (Expand Search), petrois (Expand Search)
pero » petro (Expand Search), per (Expand Search), pro (Expand Search)
petroov » petrov (Expand Search), petrioov (Expand Search), petruoov (Expand Search), petrooov (Expand Search)
petrui » petri (Expand Search), petru (Expand Search), petriui (Expand Search), petruui (Expand Search), petroui (Expand Search)
petruuou » petriuuou (Expand Search), petruuuou (Expand Search), petrouuou (Expand Search)
petruoi » petriuoi (Expand Search), petruuoi (Expand Search), petrouoi (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (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 ((petris OR (pero OR petroov)) OR ((petruuou OR (petrui OR petruoi)) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petris OR (pero OR petroov)) OR ((petruuou OR (petrui OR petruoi)) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petris OR (pero OR petroov)) OR ((petruuou OR (petrui OR petruoi)) OR (petr OR peter))) o.s.*.