How to categorize citation irregularities: A proposal based on an exploration of the literature

BACKGORUND: Citation irregularities undermine the fairness and reliability of scholarly communication, yet the terms used to describe these behaviors remain fragmented and inconsistently defined. METHODS: We employed a backward‑snowballing strategy to identify relevant publications on the historical development of views on citation irregularities, with particular attention to the literal meaning and the conceptual evolution of terms. RESULTS: Through an inductive analysis of the 50 distinct terms identified, we propose a classification consisting of nine categories: mis-citation, citation distortion, uncritical citation, irrelevant citation, excessive self-citation, citation manipulation, selective citation, coercive citation, and bibliographic plagiarism. CONCLUSIONS: The classification functions as a multi‑dimensional descriptive tool, and an instance of citation irregularity may fall into more than one category. This classification helps to clarify citation irregularities and provides a structured framework for understanding their underlying patterns.