GENERAL:
'Principles of Communism' by Frederik Engels (brief)
http://www.newyouth.com/archives/the..._communism.asp
'Workshop Talks' by James Connolly (brief)
http://www.newyouth.com/archives/cla...hop_talks.html
'Imperialism, the Highest Stage of Capitalism' by Vladmir Lenin
http://www.marxists.org/archive/leni...-hsc/index.htm
USSR:
'In Defence of the Russian Revolution' by Leon Trotsky
http://www.marxist.com/History/copenhagen.html
'Lenin and Trotsky - What they really stood for' by Allan Woods and Ted Grant
http://www.marxist.com/LeninAndTrotsky/
SCIENCE:
'Reason in Revolt: Marxism and Modern Science' by Alan Woods and Ted Grant
http://www.marxist.com/rircontents.asp
FAQ:
http://www.newyouth.com/archives/theory/marxismfaq.asp