Black Holes: The Key to Understanding the Universe

The individual or group credited with creating the main content of a product, such as a book, film, or other creative work. The value is a free‑text string representing the name(s) of the primary creator.

Indicates the physical or digital format in which a product is presented, such as "Hardback", "Paperback", "DVD", "Blu‑ray", "Vinyl", or other media types. The value may contain multiple comma‑separated items to represent combined attributes (e.g., "Hardback, Illustrated").

The name of the publishing house or imprint that released the product, such as a book or audio edition.

The mass of the product expressed in a standard unit such as grams or kilograms. It represents how heavy the item is and can be used for shipping calculations, handling instructions, or consumer information.