Power is back on in Spain and Portugal, but questions remain about Monday’s blackout. Here’s what we know  CNNMassive power outage hits Spain and Portugal  The Washington PostWhat We Know About the Power Outage in Spain and Portugal  The New York TimesSpain, Portugal switch back on, seek answers after biggest ever blackout  ReutersPower returns to Spain and Portugal. The outage’s cause remains a mystery  AP NewsPhotos: Millions without power in Spain, Portugal after 'induced atmospheric vibration'  USA TodaySpain and Portugal begin recovering from a massive blackout. Here's what to know  NPRThe lights are back on in Spain and Portugal, but nobody knows why they went out  NBC NewsPower outage in Spain and Portugal still a mystery, but leaders vow to solve it and prevent a recurrence  CBS News