I have a good to very good condition The American Language by H. L. Mencken. hardcover 1937 - 4th edition
It is a comprehensive treatise on the American dialect of English.
This specific copy is a "Corrected Enlarged and Rewritten" version, an entirely new edition running to 800 pages.
The work is known for its detailed analysis of American English, including vocabulary, syntax, idiom, and slang