Betsis, Andrew. IELTS : the vocabulary files : English usage advanced : students book : c1 / Andrew Betsis, Lawrence Mamas. - United Kingdom : Global ELT. - 64 p. : ill. ; 29 cm. Score: 6.0 - 6.5 - 7.0. ISBN: 9781904663454 Subjects--Topical Terms: English language--usage.