This is a small collection of essays on Nonsense literature. Suggestions are welcome.

[Fanny Kemble and Lear in Italy] , Littel's Living Age, vol XV, October-November-December 1847, pp. 481-94. A review of Lear's Illustrated Excursions in Italy originally published in the Quarterly Review (pdf download).

"Word-Twisting vs Nonsense." Littel's Living Age, Fifth Series, vol. LVIII (CLXXIII), April-May-June 1887: 379-81. Reprinted from The Spectator. Page images available at Cornell University Making of America:
here .) 

"A Very Good Children's Book." The Nation, 11 January 1865: 54-55.

"Nonsense." Scribners monthly, an illustrated magazine for the people,  Volume 2, Issue 6, October 1871, pp. 668-9 (pdf download).

William T. Dobson, "Nonsense Verse, &c." Literary Frivolities, Fancies, Follies, and Frolics. London: Chatto and Windus, 1880, pp. 158-175.

(Sir Edward Strachey), "Nonsense As A Fine Art." Littel's Living Age. Fifth Series, Volume LXIV, Oct-Nov-Dec 1888, pp. 515-53 (pdf download).

"Concerning Nonsense." All the Year Round. February 2, 1889, pp. 115-7. 

W. Beattie-Kingston, "Delightful Nonsense." A Journalist's Jottings. London: Chapman and Hall, 1890. Vol. 2:242-8. 

G.K. Chesterton, "A Defence of Nonsense." The Defendant. Second edition. London: R. Brimley Johnson, 1902.

Florence Milner, "The Poems in Alice in Wonderland." The Bookman XVIII, September 1903, pp. 13-6.

Carolyn Wells, "Limericks." Frank Leslie's Popular Monthly, vol. 55, no. 5, March 1903, pp. 532-5.

G.K. Chesterton, "Two Kinds of Paradox. " Illustrated London News, 11 March 1911. Reprinted in Lawrence J. Clipper (ed.), The Collected Works of G. K. Chesterton XXIX: The Illustrated London News 1911-1913. San Francisco: Ignatius Press, 1988, pp 51-54.

Holbrook Jackson, "Masters of Nonsense." All Manner of Folks: Interpretations and Studies. London: Grant Richards Ltd., 1912; pp. 30-44.

Hildegarde Hawthorne, "A New Achievement in an Old Medium: Gustave Verbeek's Monotypes." The Century Magazine 92.2, June 1916, 96-102.

Hildegarde Hawthorne, "Edward Lear." St. Nicholas: A Monthly Magazine for Boys and Girls, Volume XLIV, part I, November 1916 - April 1917, pp. 71-3.

Bertha Coolidge, "How Pleasant to Know Mr Lear!" The Colophon. A Book Collectors' Quarterly. Part Nine. New York, 1932.

G.K. Chesterton, "Both Sides of the Looking-Glass." The Listener 29 November 1933. 

Philip Hofer , "Peter Newell's Pictures & Rhymes." The Colophon. A Book Collectors' Quarterly. Part Nineteen. New York, 1934.

G.K. Chesterton, "Humour." Encyclopedia Britannica. 1939. 

George Orwell, "Nonsense Poetry." Tribune, 21 December 1945, republished in Shooting an Elephant and Other Essays. London: Sacker and Warburg, 1950: 179-84.

Marco Graziosi, "Testo verbale e testo iconico nei limericks di Edward Lear." Thesis. Università degli Studi di Bologna. Facoltà di Lettere e Filosofia. 1982 (pdf download).
Creative Commons Attribution-NoDerivs 2.5 License. 

Michele Sala, "Lear's Nonsense: Beyond Children's Literature." nonsenselit.org. 2000.
Creative Commons Attribution-NoDerivs 2.5 License.

Winfried Nöth, "The Art of Self-Reference in Edward Lear's Limericks."   Interdisciplinary Journal for Germanic Linguistics and Semiotic Analysis 10.1, 2005, pp. 47-66 (pdf download).
Creative Commons Attribution-NoDerivs 2.5 License.