German book about redheads

The book is Die Rothaarigen: Die Logik des Widersprüchlichen. Versuch einer Deutung der rothaarigen und der keltischen Menschen (which can be translated as Redheads: The Logic of the Contradictory. Attempt at an interpretation of the red-haired and the Celtic people), published in 1960 and written by author Hans Bernhard Schiff (born Wolfgang Geyse, 1915 - 1996). 

Unfortunately, the book is available only in German, so, if you know the language, you can easily find it second-hand (for example here). Should you read it, let us know what it is about!