sentences:  Trickett repeatedly criticises "orthodox academics" for ignoring or denigrating the theory of Portuguese discovery of Australia, while acknowledging that the book is "not written as an academic treatise—it is aimed at a wider audience".Trickett's approach of using only one Dieppe map as the basis for his book, without significant reference to any of the other existing Dieppe maps, has been questioned.The Vallard map of 1547 is not the first of the Dieppe maps, and Richardson argues Trickett incorrectly "assumes the unknown Vallard cartographer had access to much more information" because it contains more place names.