DeCourcy, Ken: Blue Spotitis and Other Oddities ©1980 Supreme Magic Co. Ltd, Bideford, England Softcover, saddle-stitched, 7.5x9.5", 20 pages

Image courtesy eBay seller PGProductions

Comments: Magic tricks using the paper fold "the salt cellar". Available as an eBook from Lybrary.com

Contents (from book, updated Dec 2019):

3 Introduction: sources from Robert Harbin's Paper Magic and more
4 The Salt-Cellar Folder: how to fold and basic operation
5 Colour Change: a basic effect with ideas to enhance using a silk
5 The Psychic Square: one spectator determines another's selected card
6 Coin Vanish: using the paper fold to vanish a coin
6 Coin Production: as a production
6 Married Sponges: to produce additional sponges
7 Diagrams: to page 14
15 The Oracle: using colors and numbers, can be used to tell fortunes
16 Blue Spotis, or Azure Acne: fold used to produce and vanish contagious blue spots
17 The Cat: enhancing the fold to make a vent animal or to select the chosen card
18 The Magic Carpet: a story with a different paper fold that ends in a coin production