Early access means that before the official publication, an accepted article is published online in advance, which is the preparatory version for official publication. Early access articles have been strictly reviewed, and then accepted by the journal. The contents of these articles are protected by the Copyright Law. Early access articles are not typeset and edited, and there may be some differences in text and layout from the officially published version, but the main content of the early access and officially published versions is identical.
When readers study or quote early access articles, the officially published version shall be quoted.