Perhaps you should try some spelling variations:
petris » peteris (Expand Search), petruis (Expand Search), petrois (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petroi » peteroi (Expand Search), petruoi (Expand Search), petrooi (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petrooi » peterooi (Expand Search), petruooi (Expand Search), petroooi (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
peteroi » peterdi (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 petr) OR petris) OR (((petroi OR petrooi) OR peteroi) OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petris OR petr) OR petris) OR (((petroi OR petrooi) OR peteroi) OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petris OR petr) OR petris) OR (((petroi OR petrooi) OR peteroi) OR petri)) o.s.*.