Possibly helpful:
Starting Out: Slav & Semi-Slav by Glenn Flear
Play the Slav by James Vigus (2008)
https://web.archive.org/web/20140627113701/http://www.chesscafe.com/text/hansen113.pdf
The Slav: Move by Move by Cyrus Lakdawaka (2011)
https://web.archive.org/web/20140627104306/http://www.chesscafe.com/text/hansen151.pdf
I'm looking for training material on the Slav defence but can't find much here in chess.com
there are great video series here but not on Slav defence what seems strange because it's such a popular and solid opening for black.
Aby suggestions?