the twelve caliphs

.إِنَّا غَيْرُ مُهمِلِينَ لِمُرَاعَاتِكُم وَ لَا نَاسِي

There are repeated Traditions in the Sunni and Shi’ite books in our hands today which speak about caliphate of the twelve imams and caliphs after the Holy Prophet...