Frankl identifies three sources of meaning: work, love, and courage during difficult times
Groening found guilty in July 2015 of being accessory to the murders of 300,000 Jews
The delegation, including two Sunni imams, walked through the camp's infamous wrought iron "Arbeit Macht Frei" gate
More than 70 years after World War II, Hanning stands accused of complicity at the death camp in Nazi-occupied Poland