HARDING, Keith a Alastair LANE. International express: intermediate : student's book with pocket book and DVD-ROM. 3rd ed. Oxford: Oxford University Press, 2014. ISBN 9780194597609.
MASCULL, Bill a George BETHELL. Business vocabulary in use: intermediate. 2nd ed. Cambridge: Cambridge University Press, 2010. ISBN 978-0-521-74862-9.