Chicago is the referencing style recommended by the Centre for Modern History at City, University of London.
Cite Them Right Online
Cite Them Right is a comprehensive guide to referencing almost anything you will come across in the course of your studies or research. It covers different referencing styles. It will help you to reference books, journals, articles, web sites and other material, and understand how to avoid plagiarism. You can also find answers to common questions about referencing, as well as helpful guidance to keep you on the right track.
There are also print copies available at shelf number 808.027 PEA
RefWorks is an online reference management tool that will help you gather, organise and store different type of information and it will enable you to easily generate citations and bibliography.