This nude alphabet was published as a Quadrat Print. They were a series of experimental graphic design publication edited by Pieter Brattinga and given away by the Hilversum printer de Jong from the early fifties to the mid-seventies. Each one was ten inches square, mostly several stapled pages but some were loose leaf sheets (this alphabet) in a box or folder.
Diter Rot, with issue twelve, had sixty loose pages of newspaper stock reproducing hugely enlarged sections of the Daily Mirror, a leading British tabloid. Issue six (1953) by Bruno Munari was what he called an Unreadble book of sixteen pages using alternate red and white card with each page cut into various geometric shapes and widths so you could create your abstract designs as the pages were turned.
The alphabet was created by Anthon and Anna Beeke and photographed by Geert Kooiman. Published as Quadrat Print fourteen in 1970. The thirty square loose pages were presented in a folder with a blank cover which opened up to three pages with photos of the shoot. Nicely each letter was printed on card stock rather than paper, litho with a 150 screen.