Legal treatises dealing with broad areas of the law provide a useful introduction when researching. A well-referenced book serves as a starting point from which you can move on to periodical articles, cases and statutes. To keep information up-to-date, some law publishers issue texts in loose-leaf format (book-sized binders which allow pages with out-of-date information to be replaced periodically by newer pages with up-to-date information) or as ebooks that updated multiple times per year. There are also books dedicated to the consideration of particular statutes. The latter will typically include the full text of the statute(s) in addition to commentary, history, and references to judicial consideration of the statute(s). This is often called an "annotation."
In addition to the titles issued by commercial publishers, a lot of useful literature is published by professional associations. The Canadian Bar Association and the Law Society of Ontario, for example, regularly publish seminar papers. Government publications, such as those from law reform commissions, justice departments and government inquiries, are also good sources for discussion of legal topics, including proposed changes to the law.