Seligman on Income Tax

A copy of ERA Seligman's The income tax : a study of the history, theory and practice of income taxation at home and abroad is available here at the time of writing.

Law Society paper on tax governance

The Law Society published an important document in March 2008 entitled Tax: Good Governance and better law making: A manifesto for improving tax law, which is available at page 44/190 of the linked document.