  Open-domain generative systems have gained significant attention in the field
of conversational AI (e.g., generative search engines). This paper presents a
comprehensive review of the attribution mechanisms employed by these systems,
particularly large language models. Though attribution or citation improve the
factuality and verifiability, issues like ambiguous knowledge reservoirs,
inherent biases, and the drawbacks of excessive attribution can hinder the
effectiveness of these systems. The aim of this survey is to provide valuable
insights for researchers, aiding in the refinement of attribution methodologies
to enhance the reliability and veracity of responses generated by open-domain
generative systems. We believe that this field is still in its early stages;
hence, we maintain a repository to keep track of ongoing studies at
https://github.com/HITsz-TMG/awesome-llm-attributions.
