Is walt whitman about to make a comeback? He takes center stage in Michael Cunningham's latest novel, "Specimen Days" (June 7)-- and you remember what happened when Cunningham put Virginia Woolf in "The Hours." (Everyone rushed to read, or reread, "Mrs. Dalloway.") Stay ahead of the pack: Whitman is best known for "Leaves of Grass"--his collection of poems, first published in 1855, about nature and mankind. You might want to brush up, because excerpts appear in Cunningham's novel. To learn more about the poet's life, try "Walt Whitman's America: A Cultural Biography" by David S. Reynolds. The Walt Whitman Archive (whitmanarchive.org) includes manuscripts, criticism and even an audio recording. And the Library of Congress (loc.gov) has opened a new exhibit called "Revising Himself," devoted to Whitman and "Leaves of Grass." Emerson would be proud.