A2 - B1 levels

•  English Grammar in Use Book with Answers, Cambridge University Press, Fourth Edition.
  Autore: Murphy.  ISBN: 9780521189064
• English Vocabulary in Use Pre-Intermediate and Intermediate with Answers. Cambridge University Press, Third Edition. Autore: Redman. ISBN: 9780521149884

B2 levels

• Language Practice for First, MacMillan. Author: Vince, M. ISBN: 9780230463752
• English Vocabulary in Use Upper-intermediate & Advanced, Cambridge University Press. Authors: McCarthy, M.; O’Dell, F. ISBN: 9781107600942

C1-C2 levels

• Language Practice New Edition C1 Student's Book Pack with Macmillan Practice Online and Answer Key. Author: Vince, M. Edition: MacMillan. ISBN: 9780230463813
• English Vocabulary in Use Advanced with CD-ROM 2nd Edition. Authors: McCarthy, M. & O’Dell, F., Edition: Cambridge University Press. ISBN: 9781107637764
• Advanced English Grammar in Use Third edition, Paperback with answers. Cambridge University Press. Author: Hewings, M. ISBN: 9781107697386
• Practical English Usage, Oxford University Press. Author: Swan, M. ISBN: 9780194420983

Monolingual dictionaries

for example, Oxford, Cambridge, MacMillan, Longman, etc.

• up to B1 level: Oxford Wordpower Dictionary, 4th Edition (with CD-ROM).  ISBN: 9780194398237
• up to B2 level: Oxford Advanced Learner's Dictionary: Con DVD, 2015. ISBN-13: 978-0194798792

Bi-lingual English-Italian dictionaries:

• Grande dizionario di inglese. Inglese-italiano, italiano-inglese. Con aggiornamento online. Author: Fernando Picchi. Hoepli, 5th edition, 2016.  ISBN-13: 978-8820372187
• Il Ragazzini 2017. Dizionario inglese-italiano, italiano-inglese. Author: Giuseppe Ragazzini, 2016. ISBN-13: 978-8808737373
• Garzanti Hazon di inglese 2006. Inglese-italiano, italiano-inglese. Con CD-ROM. Author: Albertini. ISBN-13: 978-8848001212

Free online dictionaries:

http://www.oxfordlearnersdictionaries.com/
http://www.macmillandictionary.com/
http://dictionary.cambridge.org/it/
http://www.wordreference.com/
http://www.merriam-webster.com/

Some of the following sites are available in both English and Italian:

https://www.britishcouncil.it/esami/ielts
http://www.cambridgeenglish.org/exams/
http://www.cambridgeenglish.org/learning-english/exam-preparation/
http://www.toeflgoanywhere.org/
http://www.trinitycollege.it/esami/
http://www.cityandguildsenglish.com/
http://pearsonpte.com/

The following is a site containing examples of various types of international certification:  http://www.examenglish.com/  

Some sites are free and are available as downloadable mobile phone apps:

http://www.bbc.co.uk/learningenglish/
http://www.cambridgeenglish.org/learning-english/
http://learnenglish.britishcouncil.org/en/
https://elt.oup.com/learning_resources/
https://www.duolingo.com/
http://www.gcflearnfree.org/topics/everydaylife/
http://www.englishcentral.com/videos
http://www.english-for-students.com/
http://a4esl.org/
https://www.englishclub.com/

Site containing information on MEC, the online course promoted by UNITN, which is used for Blended courses and for self-study on purchase of a login ID and password.

http://www.macmillanenglishcampus.com/

Some newspapers

http://www.theguardian.com/uk
http://www.thetimes.co.uk/
http://www.telegraph.co.uk/
http://www.independent.co.uk/
http://www.dailymail.co.uk/
http://www.irishtimes.com/
https://www.washingtonpost.com/

TV, Radio and podcast

http://www.bbc.com/
http://www.bbcworldwide.com/
http://www.bbc.co.uk/podcasts
http://www.ted.com/
http://edition.cnn.com/
http://news.sky.com/
https://www.youtube.com/watch?v=Ge7c7otG2mk