Physicists Are Unraveling The Great Mystery of Earth's Inner Core  ScienceAlertThe Earth’s inner core is a total mystery – here’s how we’re starting to solve it  The ConversationMysterious 'donut' structure is discovered hidden inside Earth's core  MSNVast ‘doughnut’ discovered in molten metal of Earth’s core  The GuardianSeismic echoes reveal a mysterious ‘donut’ inside Earth’s core  The Conversation