IELTS (International English Languange Testing System)

1. http://www.britishcouncil.org/es/colombia-examenes-nuestros-examenes-ielts.htm

2.  http://www.educationusa.info/faq.php?id=3&iq=709&language=3

ANALYSING WRITING IN IELTS

1. http://www.ielts.org/test_takers_information/test_sample/academic_writing_sample.aspx

2. http://takeielts.britishcouncil.org/prepare-your-test/free-practice-tests/writing-practice-test-1-ielts-academic

HOW TO USE PUNCTUATION

1. http://www.englishclub.com/writing/punctuation-comma.htm

2.http://oxforddictionaries.com/words/punctuation