A long-running lawsuit, now returning to trial, pits “Stuart Y. Silverstein, a Los Angeles lawyer who researched and assembled 122 previously uncollected poems and verses in the book ‘Not Much Fun: The Lost Poems of Dorothy Parker,’ against Penguin Putnam, which published ‘Dorothy Parker, Complete Poems,’ and used Mr. Silverstein’s book as a source for the last chapter without giving him any credit or paying him any royalties.”