Cushman, Stephen, "A. R. Ammons, or the Rigid Lines of the Free and Easy," in Critical Essays on A. R. Ammons, edited by Robert Kirschten, G. K. Hall, 1997, pp. 271-308, originally published in Fictions of Form in American Poetry, Princeton University Press, 1993, pp. 149-86.

Cushman examines one section of one of Ammons's
longer works, showing the interplay between free
verse and the poet's sense of structure, which sneaks
into his work at discreet moments.

Holder, Alan, "Plundering Stranger," in A. R. Ammons, Twayne's United States Authors Series, No. 303, Twayne Publishers, 1978, pp. 74-89.

In this relatively early survey of Ammons's works,
Holder focuses on the various ways in which nature
is used in the poet's works.

Kirschten, Robert, "Ammons's Sumerian Songs: Desert Laments and Eastern Quests," in his Approaching Prayer: Ritual and the Shape of Myth in A. R. Ammons and James Dickey, Louisiana State University Press...