Perhaps you should try some spelling variations:
petero » peter (Expand Search), peters (Expand Search), petro (Expand Search)
petris » peteris (Expand Search), petruis (Expand Search), petrois (Expand Search)
petruis » peteruis (Expand Search), petruuis (Expand Search), petrouis (Expand Search)
petrouo » peterouo (Expand Search), petruouo (Expand Search), petroouo (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)

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 petruis) OR (((petrouo OR petrouo) OR petero) OR (petr OR petri))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petris OR petruis) OR (((petrouo OR petrouo) OR petero) OR (petr OR petri))) o.s.*".