The claim that logical positivism is widely considered defunct in contemporary philosophy is a well-established and uncontroversial historical observation, rendering citation unnecessary.
The claim is a standard historical fact about the evolution of 20th-century analytic philosophy (superseded by post-positivism, Quine, Popper, etc.). None of the retrieved papers directly evaluate the general academic status of logical positivism as defunct, but the proposition is a matter of basic historiographical observation in philosophy, making it common knowledge in the context of academic history.