How were Al-Hasan and Al-Husayn (may Allah be pleased with them) killed, where were they buried, and what are the reliable sources that can be used to find this out?

Al-Hasan ibn Ali ibn Abi Talib was born in Ramadan of the 3rd year A.H. He narrated several hadiths from the Prophet, peace and blessings be upon him, including the Qunut supplication. There is a difference of opinion regarding the year of his death, between 49 A.H. and 58 A.H. It was said that he died poisoned and was buried in Al-Baqi'.

As for Al-Husayn ibn Ali ibn Abi Talib, he was born in Sha'ban of the 4th year A.H. and narrated hadiths from the Prophet, peace and blessings be upon him. He was killed on the day of Ashura in the 61st year A.H. and was buried in Karbala.

Many hadiths have been narrated concerning their virtues, among them the saying of the Prophet, peace and blessings be upon him: "These two are my sons and the sons of my daughter. O Allah, I love them, so love them and love those who love them," and his saying: "Al-Hasan and Al-Husayn are the masters of the youth of Paradise." The Prophet, peace and blessings be upon him, also prophesied that Al-Hasan would reconcile two great factions of Muslims, and he said about them: "They are my two sweet-smelling flowers in this world."