A Critical Exposition of the Philosophy of Leibniz (excerpts: prefaces 1900, 1937, ch. 1)
(engl.)
at Digital Text International
[www.ditext.com/russell/leib-t.html]

A Debate on the Argument from Contingency (interview)
(engl.)
at Digital Text International
[www.ditext.com/russell/debate.html]

On Denoting (article)
(engl.)
at Digital Text International
[www.ditext.com/russell/debate.html]

The Philosophical Importance of Mathematical Logic (articles)
(engl.)
at Marxists Internet Archive
[www.marxists.org/reference/subject/philosophy/works/en/russell.htm]

Theory of Knowledge (excerpt)
(engl.)
at Marxists Internet Archive
[www.marxists.org/reference/subject/philosophy/works/en/russell1.htm]