"Physics" . . . . . . "An examination of black holes that discusses what they are, what causes them, how they are discovered, and more." . . . . . . . "Introduces black holes, describing their physical features, how they were discovered, what causes them, and where they exist in space." . . "Introduces black holes, describing their physical features, how they were discovered, what causes them, and where they exist in space."@en . . "Electronic books" . . . "A black hole is not a hole" . "A black hole is not a hole"@en . . . "Juvenile works" . . . . . "Trous noirs (astronomie) Ouvrages pour la jeunesse." . . "Black holes (Astronomy)" . . "Earth Sciences" . . "Aeronautics, Astronautics & Space Science" . .