Hygiene In an unmarked envelope with sticker at seal reading 'H 34/100 P19.12'92 C.M.'. Two pieces of A4 paper folded in four and printed on both sides, an additional slip of paper, also titled Hygiene is an invitation to an event on Saturday 19th December 1992 from 7-10pm. Illustrations are in black and white and appear to be magnified biological diagrams with text and labels. 1992