* Second-Hand Black Holes May Be Hiding Across the Universe. Researchers Now Have a Way to Spot Them  ZME Science
* Gravitational waves reveal hidden populations within black hole mergers  Phys.org
* Evidence Mounts for Hierarchical Black Hole Mergers  American Physical Society
* Scientists Say Some Black Holes Are Born From Other Black Holes  Gizmodo
* Many black holes may not be born the way we thought  Tech Explorist
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