Some style guides specify the Oxford Dictionary, instead of Chambers. Although many of us now have access to the Complete Oxford Dictionary (and associated reference books) online, it often helps, if you are working on-screen, to spread things out by having a dictionary in book form on your desk or a side-table.
http://www.amazon.co.uk/Oxford-Dictionary-English-Dictionaries/dp/0199571120/ref=sr_1_3?ie=UTF8&qid=1366989455&sr=8-3&keywords=Oxford+english+dictionary
http://www.amazon.co.uk/Oxford-Dictionary-English-Dictionaries/dp/0199571120/ref=sr_1_3?ie=UTF8&qid=1366989455&sr=8-3&keywords=Oxford+english+dictionary