Click all for bigger.
Whoah, psychedelic! Above is not the 1st edition, which also has a fantastically stupid cover. It's safe to say this dates from the late 60s.
I love this cover for Vulcan's Hammer, also not a first edition, probably from the mid 60s:
How can you not love that they used an illustration of a guy actually brandishing a hammer! I guess what this proves is that exploitative second-runs of Philip K. Dick paperbacks are much cooler than the originals. Case in point.
Also, please compare the exuberance above with the tasteful yet boring and pointless covers of the modern editions.