Is the AOP version of the article definitive?

Yes. Different publishers have different policies. NPG's Advance Online Publication is the final version of the paper, exactly as it will be published in the issue edition. The paper is thus complete in every respect except that it does not have a volume/issue/page range. The paper does have a DOI (Digital Object Identifier) therefore it can be referenced as soon as it appears on the AOP site by using the DOI.


What are the page numbers that appear in PDFs of AOP papers?

For convenience, the PDF version of every AOP article is given a temporary pagination, beginning with page 1. This is unrelated to the final pagination in the issue.


What is the paper's official publication date?

For legal purposes (for example, establishing intellectual property rights), we assume that online publication constitutes public disclosure. But this is for the courts to decide; NPG's role as a publisher is to provide clear documentation of the publication history of a paper, both online and in print.


Must I subscribe to the journal in order to read AOP articles?

Yes. AOP papers are the same as those in the issues: while abstracts are freely available on any NPG journal's website, access to the full-text article requires a paid subscription or a site license.


How does AOP affect the calculation of Impact Factors?

Impact factors are calculated by Thomson Reuters (formerly ISI). At present, Thomson Reuters bases its calculations on the date of print publication alone, so until or unless Thomson Reuters changes its policy, AOP has no effect on Impact Factors.
See the Thomson Reuters site for a full explanation of how impact factors are calculated.


About Digital Object Identifiers

A digital object identifier (DOI) is an international, public, "persistent identifier of intellectual property entities" in the form of a combination of numbers and letters. For NPG content the DOI is assigned to an item of editorial content, providing a unique and persistent identifier for that item. The DOI system is administered by the International DOI Foundation, a not-for-profit organization. CrossRef, a not-for-profit organization, makes the DOI a reference linking standard and enables cross-publisher linking. It also maintains the lookup system for DOIs. NPG is a founding, and board, member of CrossRef.

Can I use the DOI in a reference citation?

Yes. Digital content may be referenced by providing the paper's DOI at the end of the citation. For example:

[Author(s)]. [Title]. Gene Therapy advance online publication, [publication date]; doi:[DOI].


[Author(s)], ([Year]). [Title]. Gene Therapy [volume], [page(s)]; doi:[DOI].

How can I use a DOI to find a paper?

  • To find a paper on the platform use the paper's DOI as a Search term.
  • To resolve any DOI, go to the DOI System proxy server and enter the paper's DOI.