When a book is written collectively by numerous authors and when each author is the sole creator of a specific and complete section of the book, then an adequate footnote representing Ruskin’s section should be included in this format:
1 George P. Landow, “Title of the book’s particular section”, in A.L. Le Quesne et al., Victorian Thinkers: Carlyle, Ruskin, Arnold, Morris, Oxford: Oxford University Press, 1992, pp. xx-yy.
(Please note that “xx” is the first page number of the “Ruskin” section and “yy” is the last page number of the “Ruskin” section).
The bibliography reference would look like this:
Le Quesne, A. L. et al. Victorian thinkers: Carlyle, Ruskin, Arnold, Morris. Oxford: Oxford University Press, 1992. 428 p.