I think they messed up; the first sentences of each of the first two examples are identical apart from the reference. > Dr Johnson kicked a large rock and said

I think they messed up; the first sentences of each of the first two examples are identical apart from the reference. > Dr Johnson kicked a large rock and said, as his foot rebounded, “I refute it thus.”[1] and > Dr Johnson kicked a large rock and said, as his foot rebounded, “I refute it thus.”[3] Second one should be: Dr Johnson kicked a large rock and said, as his foot rebounded, “I refute it thus”.[3]