This is a vintage set of The Hardy Boys Series with matte covers. Missing book # 29, 33, and 58. The author is Franklin Dixon and the publisher is Grosset & Dunlap. The books are in English and the intended audience is young adults, ages 9-12, and adults. The genre is action, adventure, and mystery, with a topic of mystery. The books are in hardcover format and are part of the book series.