how to specify image size in pixels

Question

Quick question about specifying the size of images in pixels:

Answer 1

Could not find any information that verifies this but I would use integers without a unit (if not percentage) in HTML and use "px" in CSS, except for zero values where it´s more correct to leave out the unit.

http://www.w3.org/TR/CSS2/visudet.html#the-width-property