The published article may be retracted for several reasons including serious flaws in findings or conclusions, peer review manipulation, plagiarism, redundant publication, reuse of material or data without authorisation, copyright infringement, unethical research, and/or a failure to disclose a major competing interest. For any retracted article, the reason for retraction will be clearly stated in the retraction notice and linked to the retracted article. The retracted article will be clearly marked as retracted (including the PDF).