Caza - "The Fall of the Towers" (1976)

the following story is by Caza (France 1941 - ) and is taken from the first issue of a Spanish comic magazine called Bumerang.  i have been attempting to research this magazine and this particular story for days and have found very little.  apparently this story is a reprint from a Dargaud Presse publication, but i am not sure of any more than that.  any information on this story or Bumerang would be greatly appreciated.

Caza's draftsmanship and inkwork here are absolutely stunning, and his use of flat primary colors are extraordinary.  much of the story's power comes from the colors, and the striking isolation of one hue within a larger field of another.   the panel compositions, the page layouts, and the storytelling "beats" are all flawless.  Caza would later go on to be a major force in the pages of Heavy Metal in the 1980's.