The I-SPY books are spotters' guides written for British children, particularly successful in the 1950s and 1960s in their original form and again when relaunched by Michelin in 2009 after a seven-year gap in publishing. A search engine set to look for images, with the words - "i-spy" News Chronicle Daily Mail Michelin, can illustrate that a range of styles was used. Source: Wikipedia (en)