The 'four strands" by Paul Nation make a good read in addition to this article. Both are about the same vintage. Nation's article is definitely more focused on practical application in teaching a foreign language.
Sorry...here is the link to a version of the article: http://www.victoria.ac.nz/lals/staff/Publications/paul-nation/2007-Four-strands.pdf
Thank you Steve. It is actually a good complementary reading.