O'Neill M., Summers E. & Butterfield J. (2016). Collins ENGLISH DICTIONARY & GRAMMAR. Glasgow, Scotlands: Collins, An imprint of HarperCollins Publishers.
Chicago
O'Neill Mary, Summers Elspeth and Butterfield Jeremy. 2016. Collins ENGLISH DICTIONARY & GRAMMAR. Glasgow, Scotlands: Collins, An imprint of HarperCollins Publishers.
Harvard
O'Neill M., Summers E. and Butterfield J. (2016). Collins ENGLISH DICTIONARY & GRAMMAR. Glasgow, Scotlands: Collins, An imprint of HarperCollins Publishers.
MLA
O'Neill Mary, Summers Elspeth and Butterfield Jeremy. Collins ENGLISH DICTIONARY & GRAMMAR. Glasgow, Scotlands: Collins, An imprint of HarperCollins Publishers. 2016.