I can also add that Bh5 is also recommended in Dangerous Weapons : the Ruy Lopez, I accidently made a look in that book today.

During this years Swedish Championship I bought Kindermanns book on Exchange Ruy Lopez from 2005.

I bought it for the introduktion and ideas chapter to increase my generally positonal understandning, not to actually play it with either side. 

I am also considering to buy Cox book on Berlin Ruy Lopez for introduction chapter for the same reason.

I also became party interesting in this line theoretial status so I looked at Alterman Gambit Guides chapter on Hector gambit to compare the books. Interesting enough Kinderman thought that  5 0-0 Bg4 lines was blacks best line and after 6  h3 Kinderman mainly looked at and recommend h5, a line that Altermans thinks is slightly better for White. Instead Alterman wants to play 6 ..Bh5 a line Kindermann hardly looked at becouse of 7 g4 and in Altermans lines black seems to get very active play and I think I prefere to play black!

Does all Ruy Lopez exchange variation players enter the Hector gambit or do the play something else, like for example d3 instead of g4?