Perhaps you should try some spelling variations:
"testhefte e poetica" » "testheften i poetica", "testheft i poetica", "testheft der poetica", "testhefte de poetica", "testhefte et poeticae", "testhefte _ poetical"
"leithefte zu poetica" » "leithefte la poetica", "leithefte de poetica", "leithefte da poetica", "beihefte zu poetica"
"leseheft a poetica" » "leseheft zur poetica", "leseheft a poetical", "leseheft la poetica", "leseheft da poetica"
"lesehefte a poetica" » "lesehefte a poetical", "lesehefte la poetica", "lesehefte da poetica"
"lesehefte e poetica" » "lesehefte de poetica", "lesehefte et poeticae", "lesehefte _ poetical"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("leithefte zu poetica") OR ((((("lesehefte a poetica") OR ("leseheft a poetica"))) OR ((("lesehefte e poetica") OR ("testhefte e poetica")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"leithefte zu poetica\") or (((((\"lesehefte a poetica\") OR (\"leseheft a poetica\"))) or (((\"lesehefte e poetica\") or (\"testhefte e poetica\"))))))".
• Removing quotes may allow a broader search: (( leithefte zu poetica ) or ((((( lesehefte a poetica ) OR ( leseheft a poetica ))) or ((( lesehefte e poetica ) or ( testhefte e poetica )))))).
• Adding a wildcard symbol may retrieve word variants: (("leithefte zu poetica") or ((((("lesehefte a poetica") OR ("leseheft a poetica"))) or ((("lesehefte e poetica") or ("testhefte e poetica"))))))*.