I have seen these statements quoted in H. Newcomb Morse, “The Foundations and Meaning of Secession,” Stetson Law Review 15, 2 (1986), 419-36. If you’re at a university you should be able to get this article via interlibrary loan. Wish I could point you to a more convenient source.
Now opponents of secession will claim that these statements by these states amount simply to an acknowledgment of the right of revolution. This is the way the Straussians deal with these passages. This isn’t secession, they say, which in their view is an absurdity. It is simply a restatement of the Lockean principle that people may overthrow oppressive governments,