Hi tillie,

That’s an interesting find: the hollowed-out letters on the front cover are taken from a ready-made alphabet by Walter Haettenschweiler. It was shown in the fourth volume of Lettera in 1972 under the name Wornout. It’s basically Helvetica compact with rough inner contours.

Helene Silverman, the designer of the original single cover, used Wornout on both the front and back. I don’t know whether this alphabet was turned into a proper typeface for photographic or digital typesetting, or whether she reproduced the letterforms directly from the alphabet source book, for example by means of scanning.

When the EP was released, the back cover had to be updated. Apparently this was done by a different designer, who for some reason didn’t use Wornout. Instead, they made their own hollowed-out version to emulate the front cover typography. It’s based on a different cut (something like Helvetica Black Condensed or Swiss 721 Black Condensed, with added stroke) and is a tad wider and bolder than Wornout.