Perhaps you should try some spelling variations:
"schriftenreihe zur un marketing" » "schriftenreihen der un marketing", "schriftenreihe des un marketing", "schriftenreihe die un marketing", "schriftenreihe zur run marketing", "schriftenreihe zur den marketing", "schriftenreihe zur man marketing"
"schriftenreihe der und marketing" » "schriftenreihe der un marketing"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"schriftenreihe zur un marketing\") OR (\"schriftenreihe der und marketing\"))".
• Removing quotes may allow a broader search: (( schriftenreihe zur un marketing ) OR ( schriftenreihe der und marketing )).
• Adding a wildcard symbol may retrieve word variants: (("schriftenreihe zur un marketing") OR ("schriftenreihe der und marketing"))*.