​What to know about ketamine therapy after Matthew Perry’s cause of death announced  ABC NewsMatthew Perry Died of ‘Acute Effects of Ketamine,’ Autopsy Says  The New York TimesMatthew Perry’s Cause of Death Determined: “Friends” Actor Died of ‘Acute Effects of Ketamine’  PEOPLEMatthew Perry’s Cause of Death Revealed as ‘Acute Effects of Ketamine’  VarietyWhat is ketamine, the drug tied to actor Matthew Perry’s death?  NPR