For those who wish to further their understanding of liberalism as this e-book construes it, the following books are recommended:
'Liberalism' by John Gay (Open University Press, 1986) in which he argues that liberalism is a coherent body of principles, philosophy, and culture which is centered around the idea and ideal of individualism and subsequent individual rights.
'The Rise and Decline of Western Liberalism' by Anthony Arblaster (Oxford, 1984) in which he defines liberalism as, among other things, a distinctive personal temperament or cultural attitude
'Liberalism' by Ludwig von Mises (many editions, 1927) which is a highly socio-economic treatment of the subject by the foremost economist in human history
'Western Liberalism: A History in Documents From Locke to Croce' by E.K. Bramsted and K.J. Melhuish (Longman, 1975) which is by far the best one-book source for the original documents (altho' currently out of print, it's still widely available in libraries)
'An Intellectual History of Liberalism' by Pierre Manent (Princeton, 1996) which examines liberal philosophy and politics from a highly European/French perspective, but which is surprisingly up to date. Manent claims Hobbes founded modern liberalism, and argues that to solve the monumental "theologico-political problem" of tyranny, it was first necessary to defeat somewhat the philosophy of Christianity.
Unfortunately, for those who wish a highly cultural treatment of the subject, or one which also includes the clearly liberal culture of classic Greece and Rome, apparently no such book currently exists.