Which classical scholars included Hasan as the fifth rightly guided caliph?

The Messenger of Allah (saw) said:  "The caliphate will last for thirty years; after that, it will become a mulk" (Ahmad)  "The caliphate in the footsteps of prophethood will be thirty years; then Allah will give (His) power and authority to whomever He wills" (Abu Dawood)  "The caliphate in my Ummah (the nation of Muslims) will last for thirty years; thereafter, it will become mulk." (Tirmidhi)  Regarding the latter hadith, Ibn Kathir observed: "The thirty-year period was only completed with the caliphate of al-Hasan ibn Ali (ra). He gave up the caliphate to Mu'awiyah in Rabee'i 41 AH and that was the completion of thirty years after the death of the Messenger of Allah for he had died in Rabee'i 11 AH." (al-Bidayah wa al-Nihayah, 11:13) Qadi Iyad said:  During the thirty years, there were no rulers other than the four Rightly-Guided Caliphs and the few months during which allegiance was sworn to al-Hasan ibn 'Ali (i^). The hadith about the caliphate lasting for thirty years refers to the caliphate in the footsteps of prophethood, as stated in some reports: "The caliphate in the footsteps of prophethood after me will be thirty years, then it will become a mulk." (Sahih al-Muslim) " (Shifaa) Ibn Abil-Izz al-Hanafi wrote:  "The caliphate of Abu Bakr lasted for two years and three months, the caliphate of 'Umar lasted for ten and a half years, the caliphate of Uthman lasted for twelve years, the caliphate of Ali lasted for four years and nine months, and the caliphate of al-Hasan lasted for six months." (al-Adhra'i, Sharh al-Aqeeda al-Tahawiyyah, p.545) Ibn Hajar al-Haythami said:  "He is the last of the Rightly-Guided Caliphs according to the statement of his grandfather. He became the caliph after the murder of his father, with the oath of allegiance of the people of Kufa. He remained the caliph for six months and several days. He was a legitimate caliph and a just ruler who truly fulfilled what his grandfather, the truthful one (saw), had said: "The caliphate after me will be for thirty years." Those six months completed the thirty years." (al-Shaykh, Aqeeda Ahl as-Sunnah wal-Jama'ah fi al-Sahabat al-Kirdm, 2:748)   References al-Adhra'i, Sharh al-Aqeeda al-Tahawiyyah al-Shaykh, Aqeeda Ahl as-Sunnah wal-Jama'ah fi al-Sahabat al-Kirdm Ibn Kathir, al-Bidayah wa al-Nihayah