Britain. A short introduction
Bourke

Focus on Modern Business 2 Extra Pr

Longman Commercial Communication
Stanton/Wood

Englisch for You 2
Ribitsch, Horst

English in Mind 3 Workbook
Puchta, Herbert / Stranks, Jeff

So spricht der Amerikaner
Langenscheidt

Langenscheidts Grammatiktafel Engli

English Preposition Idioms
Wood

A Commercial Course
Eckersley/Kaufmann

Intermediate Listening
Timesaver