I have recently added two articles on Edward Lear to the Studies on EL page, and they are both freely available:

• Ponterotto, Diane. “Rule-Breaking and Meaning-Making in Edward Lear.” Revista Alicantina de Estudios Ingleses 6 (1993): 153-61.
• Waltrick do Amarante, Dirce. “Edward Lear e seu ‘nonsense’ errante.” Aletria – Revista de Estudos de Literatura 20, no. 2 (2010): 133-39.