Perhaps you should try some spelling variations:
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petruoi (Expand Search), petri (Expand Search), petro (Expand Search), petrov (Expand Search)
petroiv » peteroiv (Expand Search), petrioiv (Expand Search), petruoiv (Expand Search), petriv (Expand Search), petrov (Expand Search), petrovv (Expand Search)
petris » peteris (Expand Search), petriis (Expand Search), petruis (Expand Search), petri (Expand Search)
peteri » peterdi (Expand Search), peter (Expand Search), petri (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 ((petroi OR peteri) OR ((petroiv OR petroiv) OR (petris OR petris)))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (petr OR ((petroi OR peteri) OR ((petroiv OR petroiv) OR (petris OR petris)))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (petr OR ((petroi OR peteri) OR ((petroiv OR petroiv) OR (petris OR petris)))) o.s.*.