There was a trademark issue with "Astro" and "astroturf" that turned those players into "Houston" for about four or five years with Topps. I can see the A's being screwy due to the Oakland move but the lack of some team cards is puzzling. It's almost like Topps missed half a series in there.
In a 7 series sets, you would have 2-3 team cards per series back then; I wonder if there were production issues in '68-the changing of the burlap borders after series 1 certainly points to some kind of problem. I agree there should have been more cards, not less in '68.
There were no Houston team cards from 64-67 either. I have more on this here:
http://toppsarchives.blogspot.com/se...os%20Wackiness