One of the best books ever written, after Strunk and White, is The Reader Over Your Shoulder by Robert Graves and Alan hodge. It was first published in the 1940's, in London. Although it is particularly English -- that is, British -- in its examples it offers wonderful examples and insights into the art of disciplined writing.

An excerpt of their principles for clarity and grace in writing can be found here. But the whole book is full of gems.

Regards,

A