Samuel Warren: The Opium Question (London: James Ridgway 1840)
- Digitized:
> Google Books (Original from British Library, digitized 14 August 2013)
> Google Books (Original from University of Minnesota, digitized 7 July 2010)
> Internet Archive
> Google Books
> Google Books (Original from Harvard University, digitized 24 August 2007) - Bibliographic reference: BS 1905
- No copy listed in Wiener Chinabibliographie
Sir Sydney Smith Bell: Answer … to The Opium Question by Samuel Warren (London: Smith, Elder & Company 1840)
- Digitized: Google Books (Original from British Library, digitized 23 July 2013)