Pope Eugene IV, Council of Florence, “Letentur coeli,” Sess. 6, July 6, 1439, ex cathedra: “We define also that… the souls of those who depart this life in actual mortal sin, or in original sin alone, go straightaway to hell, but to undergo punishments of different kinds.”
Pope Paul III, The Council of Trent, Sess. 7, Can. 5 on the Sacrament of Baptism, ex cathedra: “If anyone says that baptism [the Sacrament] is optional, that is, not necessary for salvation (cf. Jn. 3:5): let him be anathema.”
Pope Eugene IV, The Council of Florence, “Exultate Deo,” Nov. 22, 1439: “Holy baptism, which is the gateway to the spiritual life, holds the first place among all the sacraments; through it we are made members of Christ and of the body of the Church. And since death entered the universe through the first man, ‘unless we are born again of water and the Spirit, we cannot,’ as the Truth says, ‘enter into the kingdom of heaven’ [John 3:5]. The matter of this sacrament is real and natural water.”
The sources are cited. I trust you can search for the links as well as I can. If you find a translation that seems to convey a different meaning, please let me know.