I bought these little samples a couple of years back from e-bay; there are seven (plus tow crochet ones), each has typed instrutcions and a little knitted sample very neatly handsewn underneath to illustrate the stitch. Some are stamped "registered at stationers' hall", and some have a little sticker on saying 6 1/2 (could be a price, maybe, sixpence ha'penny?. Strangely, the titles of the samples are Spanish words - ovalado, angelica, malvina, campanillas, hoja, cuadritos, adela. They're lovely things to have, and I'm using them as part of our sample knit-along on Creative Living forum.
Difficult to date accurately - the seller on e-bay didn't know much about them - but I reckon 1950s or 60s.
I'd love to know more about them - who made them and why, but in teh end it's enough that I have them to save for future knitters.