The other references are great. Here is another.
The main point of what has been said is this: we have such a high priest, who has taken his seat at the right hand of the throne of the Majesty in heaven, a minister of the sanctuary and of the true tabernacle that the Lord, not man, set up. Now every high priest is appointed to offer gifts and sacrifices; thus the necessity for this one also to have something to offer. (Heb 8:1-3)
Jesus is described as “High Priest.” But in order to be a priest, “it is necessary for Him to have something to offer.” As minister in the sanctuary He is offering up (present tense) His eternal sacrifice to the Father which is perfected in heaven.
Therefore, it was necessary for the copies of the heavenly things to be purified by these rites, but the heavenly things themselves by better sacrifices than these. For Christ did not enter into a sanctuary made by hands, a copy of the true one, but heaven itself, that he might now appear before God on our behalf. Not that he might offer himself repeatedly, as the high priest enters each year into the sanctuary with blood that is not his own; if that were so, he would have had to suffer repeatedly from the foundation of the world. But now once for all he has appeared at the end of the ages to take away sin by his sacrifice. (Heb 9:23-26)
Jesus’ sacrifice, which is presented eternally to the Father in heaven, is described as “sacrifices” (in the plural) in the context of its re-presentation on earth. “Once for all,” refers to Jesus’ appearance in heaven, which is perpetual, and also refers to Jesus’ suffering and death (never to be repeated). “Once for all” never refers to Jesus’ sacrifice, which is eternally presented to the Father. Through our celebration of the Mass we enter the sanctuary and join Jesus’ perpetual sacrifice.
Therefore, brothers, since through the blood of Jesus we have confidence of entrance into the sanctuary by the new and living way he opened for us through the veil, that is, his flesh, and since we have “a great priest over the house of God,” let us approach with a sincere heart and in absolute trust, with our hearts sprinkled clean from an evil conscience and our bodies washed in pure water. (Heb 10:19-22)
No, you have approached Mount Zion and the city of the living God, the heavenly Jerusalem, and countless angels in festal gathering, and the assembly of the firstborn enrolled in heaven, and God the judge of all, and the spirits of the just made perfect, and Jesus, the mediator of a new covenant, and the sprinkled blood that speaks more eloquently than that of Abel. (Heb 12:22-24)