Perhaps you should try some spelling variations:
petris » petri (Expand Search), peteris (Expand Search), petriis (Expand Search), petruis (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petriiv » peteriiv (Expand Search), petriiiv (Expand Search), petruiiv (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)
petruov » peteruov (Expand Search), petriuov (Expand Search), petruuov (Expand Search), petrov (Expand Search)
peterov » petrov (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 petruv) OR petriiv) OR (petr OR ((peterov OR petruov) OR petriiv))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petris OR petruv) OR petriiv) OR (petr OR ((peterov OR petruov) OR petriiv))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petris OR petruv) OR petriiv) OR (petr OR ((peterov OR petruov) OR petriiv))) o.s.*.