Where does it cover 1 e4 e5 2 Nf3 Nc6 3 d4 exd4 4 Nxd4 ?
"Mastering the Chess Openings", John Watson, Volume 1, pp. 63-64.
Note that Watson's series does not attempt to provide coverage of every opening, although it does treat the vast majority, in varying degrees. And of the openings it does deal with, there is no attempt to provide complete or comprehensive coverage. This series is more concerned with explicating ideas, themes and plans of the openings in general, and the analysis is impressive (IMO) for its depth and clarity. The author's point is not to cover the same ground that is detailed adequately and ad nauseum in the hundreds of other openings books which are concerned primarily with the "theory" (i.e., the variations and lines) of specific openings. If treatment of the so-called "theory" of most of the major opening is of more interest, a good (single volume) reference for that purpose would be FCO: Fundamental Chess Openings" by Paul van der Sterren.
... "Play 1 e4 e5: A Complete Repertoire for Black in the Open Games" by Nigel Davies.
https://web.archive.org/web/20140626201436/http://www.chesscafe.com/text/hansen80.pdf
https://web.archive.org/web/20140627083715/http://www.chesscafe.com/text/hansen98.pdf