How to format your references using the Ophthalmologica Extra citation style

This is a short guide how to format citations and the bibliography in a manuscript for Ophthalmologica Extra. For a complete guide how to prepare your manuscript refer to the journal's instructions to authors.

Using reference management software

Typically you don't format your citations and bibliography by hand. The easiest way is to use a reference manager:

PaperpileThe citation style is built in and you can choose it in Settings > Citation Style or Paperpile > Citation Style in Google Docs.
EndNoteFind the style here: output styles overview
Mendeley, Zotero, Papers, and othersThe style is either built in or you can download a CSL file that is supported by most references management programs.
BibTeXBibTeX syles are usually part of a LaTeX template. Check the instructions to authors if the publisher offers a LaTeX template for this journal.

Journal articles

Those examples are references to articles in scholarly journals and how they are supposed to appear in your bibliography.

Not all journals organize their published articles in volumes and issues, so these fields are optional. Some electronic journals do not provide a page range, but instead list an article identifier. In a case like this it's safe to use the article identifier instead of the page range.

A journal article with 1 author
Kasahara J. Geophysics. Tides, earthquakes, and volcanoes. Science. 2002 Jul;297(5580):348–9.
A journal article with 2 authors
Vaughn D, Strathmann RR. Predators induce cloning in echinoderm larvae. Science. 2008 Mar;319(5869):1503.
A journal article with 3 authors
Gonsamo A, Chen JM, Wu C. Citizen Science: linking the recent rapid advances of plant flowering in Canada with climate variability. Sci Rep. 2013;3:2239.
A journal article with 7 or more authors
Kapp FG, Perlin JR, Hagedorn EJ, Gansner JM, Schwarz DE, O’Connell LA, et al. Protection from UV light is an evolutionarily conserved feature of the haematopoietic niche. Nature. 2018 Jun;558(7710):445–8.

Books and book chapters

Here are examples of references for authored and edited books as well as book chapters.

An authored book
Kunz W. Species Conservation in Managed Habitats. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2016.
An edited book
Sz.-Nagy B. Harmonic Analysis of Operators on Hilbert Space. 2nd ed. New York, NY: Springer; 2010.
A chapter in an edited book
Castellano G, Torsello MA. How to Derive Fuzzy User Categories for Web Personalization. In: Castellano G, Jain LC, Fanelli AM, editors. Web Personalization in Intelligent Environments. Berlin, Heidelberg: Springer; 2009; pp 65–79.

Web sites

Sometimes references to web sites should appear directly in the text rather than in the bibliography. Refer to the Instructions to authors for Ophthalmologica Extra.

Blog post
Andrew D. Human Experiments – The Good, The Bad, And The Ugly [Internet]. IFLScience. 2016 Nov [cited 2018 Oct 30]. Available from:


This example shows the general structure used for government reports, technical reports, and scientific reports. If you can't locate the report number then it might be better to cite the report as a book. For reports it is usually not individual people that are credited as authors, but a governmental department or agency like "U. S. Food and Drug Administration" or "National Cancer Institute".

Government report
Government Accountability Office. Highway Emergency Relief: Strengthened Oversight of Project Eligibility Decisions Needed. Washington, DC: U.S. Government Printing Office; 2011.

Theses and dissertations

Theses including Ph.D. dissertations, Master's theses or Bachelor theses follow the basic format outlined below.

Doctoral dissertation
Eyers BM. An Analysis of Remote Biometric Authentication with Windows. 2011

News paper articles

Unlike scholarly journals, news papers do not usually have a volume and issue number. Instead, the full date and page number is required for a correct reference.

New York Times article
Stewart JB. Trump-Size Idea for a New President: Build Stuff. New York Times. 2016 Nov;A1.

In-text citations

References should be cited in the text by sequential numbers in square brackets:

This sentence cites one reference [1].
This sentence cites two references [1,2].
This sentence cites four references [1–4].

About the journal

Full journal titleOphthalmologica Extra
ISSN (online)2296-1445

Other styles