Perhaps you should try some spelling variations:
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petroi » petruoi (Expand Search), petrooi (Expand Search), peroi (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petriv » petruiv (Expand Search), petroiv (Expand Search), periv (Expand Search), petrov (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (Expand Search)
petrois » petruois (Expand Search), petroois (Expand Search), perois (Expand Search), petros (Expand Search), petrovs (Expand Search), petrows (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 peter) OR ((petri OR petroi) OR (petriv OR (petris OR petrois)))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petr OR peter) OR ((petri OR petroi) OR (petriv OR (petris OR petrois)))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petr OR peter) OR ((petri OR petroi) OR (petriv OR (petris OR petrois)))) o.s.*.