The reverse of a string, introduced informally above, can be defined more precisely by the recursive rules ar = a, (wa)r = awr, for all a ∈ σ, w ∈ σ*. use this to prove that (uv)r = vrur, for all u, v ∈ σ+.

How would you cite different books by the same author on the works cited page? moore, jack h. folk songs and ballads. salem: poetry press, 1999. print. moore, jack h. ballads in poetry – a critical review. dallas: garden books, 1962. print. moore, jack h. folk songs and ballads. salem: poetry press, 1999. print. –––. ballads in poetry – a critical review. dallas: garden books, 1962. print. moore, jack h. ballads in poetry – a critical review. dallas: garden books, 1962. print. moore, jack h. folk songs and ballads. salem: poetry press, 1999. print. moore, jack h. ballads in poetry – a critical review. dallas: garden books, 1962. print. –––. folk songs and ballads. salem: poetry press, 1999. print.