After Kroeger's death in 1909 the American Library Association asked Isadore Gilbert Mudge, head of the reference department for the library at Columbia University, to take over the project. Mudge started a trend at Columbia that would last for several decades, pushing their reference staff to essentially “lead four lives-as editors, administrators, collection builders, and front-line reference specialists” (Plotnik, 130). Much of the work for the Guide was accomplished alongside the normal reference work duties of collection development and assisting students and professors with their research requests. During this time the indexes on reference materials expanded and the book went through two title changes: "New Guide to Reference Books" in 1923 and "Guide to Reference Books" in 1929.