Reichart, D EPrice, Paul2015-12-132015-12-130004-637Xhttp://hdl.handle.net/1885/74612It appears that the majority of rapidly and well-localized gamma-ray bursts with undetected or dark optical afterglows ("dark bursts") occur in clouds of size R ≳ 10L491/2 pc and mass M ≳ 3 × 105L49 M⊙ where L is the isotropic-equivalent peak luminKeywords: Dust, extinction; Galaxies: starburst; Gamma rays: bursts; Infrared: galaxies; ISM: clouds; Stars: formationEvidence for a Molecular Cloud Origin of Gamma-ray Bursts: Implications for the nature of star formation in the universe200210.1086/3241562015-12-11