Perhaps you should try some spelling variations:
petriv » petris (Expand Search), petrov (Expand Search), peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petriiiv » peteriiiv (Expand Search), petruiiiv (Expand Search), petroiiiv (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petruo » peteruo (Expand Search), petruuo (Expand Search), petrouo (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petero » peter (Expand Search), peters (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 ((petriv OR petriiiv) OR (((petr OR petero) OR (petruo OR peteriuo)) OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriv OR petriiiv) OR (((petr OR petero) OR (petruo OR peteriuo)) OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriv OR petriiiv) OR (((petr OR petero) OR (petruo OR peteriuo)) OR petri)) o.s.*.