Slater was also the author of a book on investment, "The Zulu Principle", which focuses on simple techniques for identifying small dynamic growth companies whose shares are at a low price compared to their future prospects. With Hemmington Scott, he devised a monthly company statistical guide, Company REFS, also available as a daily online service, to make the identification of such shares easier for the private investor. Slater authored several other investment books, and had a side career as a children's author, writing the "A. Mazing Monsters" series.