Add ML for the Working Programmer (#5280)

books/free-programming-books.md

@@ -2848,6 +2848,7 @@ Kerridge (PDF) (email address *requested*, not required)
 ### Standard ML
 
 * [Introduction to Standard ML](http://www.pllab.riec.tohoku.ac.jp/smlsharp/smlIntroSlides.pdf) - Atsushi Ohori (PDF)
+* [ML for the Working Programmer, 2nd Edition](https://www.cl.cam.ac.uk/~lp15/MLbook/pub-details.html) - Lawrence C. Paulson
 * [Programming in Standard ML '97](http://homepages.inf.ed.ac.uk/stg/NOTES/) - Stephen Gilmore, University of Edinburgh
 * [Programming in Standard ML, DRAFT](http://www.cs.cmu.edu/~rwh/isml/book.pdf) - Robert Harper (PDF)
 * [SML# Document](http://www.pllab.riec.tohoku.ac.jp/smlsharp/docs/3.0/en/manual.xhtml) - Atsushi Ohori, Katsuhiro Ueno