Charity is one of the three theological virtues; and the other two (hope and faith) were treated in two successive encyclicals, one signed by Benedict (Spe Salvi) and one written substantially by him but signed by Deus caritas est's successor Pope Francis (Lumen fidei).
Head entity: Spe Salvi
Tail entity: Deus Caritas Est
Relation (head \u2192 tail): followed by
Inverse relation (tail \u2192 head): follows