Zubair's role in the killing of Uthman
Al-Tabari in The History of al-Tabari, V16 pp125–126
Before the Battle of the Camel, Ali confronted al-Zubayr over his demand for Uthman's blood and accused him of being responsible for Uthman's killing. Ali also rebuked Talha for bringing the wife of the Messenger of Allah (saww) to battle while leaving his own wife at home.
Ali said to al-Zubayr:
“Are you asking me for compensation for the blood of Uthman, when it was you who killed him?”
Ali then said to Talha:
“You have brought the Messenger of Allah’s wife to make her fight while you hide your wife at home.”
Ibn ʿAbd Rabbih in al-ʿIqd al-Farīd, V2 p95
Ibn ʿAbd Rabbih records that Nāʾilah bint al-Furāfiṣah, the wife of Uthman, wrote a letter to Muʿawiyah describing the events surrounding Uthman's killing. In the letter, she states that the people of Egypt had entrusted their affair Ali, Muhammad ibn Abi Bakr, Ammar ibn Yasir, Talha and al-Zubayr, and that they ordered them to kill Uthman.
وأهلُ مصر قد أسندوا أمرَهم إلى عليّ ومحمد بن أبي بكر وعمّار بن ياسر وطلحة والزُبير، فأمروهم بقتله.
Ibrahim al-Harbi in Gharib al-Hadith, V4 p24, Hadith 1114
Al-Ashtar said that Ibn al-Zubayr was the one who instigated Aisha, the Mother of the Believers, to go out.
كان الذي أز أم المؤمنين على الخروج ابن الزبير