Complex sentence: In 1952 Trease wrote a prequel "The Crown of Violet" (US title "Web of Traitors"), the title is taken from a quote from Pindar (see City of the Violet Crown).
Split into simpler sentences: In 1952 Trease wrote a prequel "The Crown of Violet" (US title "Web of Traitors"). The title is taken from a quote from Pindar (see City of the Violet Crown).