References
This place includes references used in the content of the units.
Introduction
In order to compile the 18 online units of the textbooks B2 and C1, we authors have used different text sources and contents, both original and adapted, to create activities, pages, tests, exercises and other resources. As acknowledgement to the authors of the used resources, we would like to express our thanks. Please contact us if you have any query or copyright clarifying request.