Although it is not possible to be certain without seeing the actual text that you are working from, it is likely that the numbers in the brackets are referring to works that are listed later in a bibliography. In other words, there is probably a list of citations at the end of the work you are referring to. That list is numbered. You will be able to look at this numbered list and see reference #1 and reference #22. These are the works that are being cited in support of the statement.
What you should do, then, is to look at the end of the work and see if there is a numbered list with full citations.