How can/should I indicate that it's okay to use open access content in a paper? Suppose I want to reuse some substantial piece of content - say, a figure1 - from someone else's paper in my own scholarly work. If the other paper is under a traditional license, I'll have to obtain explicit permission from the copyright holder (usually the publisher), and then when I include the figure in my own work, I can say "Figure from reference [x], used with permission."

However, if the other paper is under an open access license or is in the public domain, and my own work will be released under a compatible license, I don't need to explicitly contact the copyright holder to ask for permission to use their content. When I attribute the figure in my work, can I still say "used with permission"? Legally speaking, I do have permission to use it by virtue of the license under which it is released (or lack thereof, if public domain), but including that phrase makes it sound like I've received an explicit statement of permission from the copyright holder, and I wouldn't want to give a misleading impression about that.

If I shouldn't say "used with permission," what would be a suitable replacement? If it's under a Creative Commons license, for example, I could say something like


  Figure from reference [x], used under the terms of the Creative Commons Attribution 4.0 license


but that seems a little verbose. Is there a better alternative?

I'm also interested in how to handle this when the content is in the public domain, or is under a much more permissive open access license (perhaps one whose attribution requirement is merely "you must credit the author"). I understand that I'm not legally required to include any notice saying that I'm allowed to use content under such a license. But for this question I'm more interested in the ethical obligations that a reader might perceive.



1Even though a single figure would often be considered fair use. But let's pretend for this question that whatever I want to reuse is enough that fair use doesn't apply.

This question concerns a similar situation, but is asking about whether it is legal to reuse content at all, whereas I'm asking about how to properly show that it is legal to do so, after it's been established that no explicit permission is necessary.
Almost all CC licenses include an attribution clause. As of the 4.0 version, this means:


  Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.


Clicking the "appropriate credit" shows some more information:


  If supplied, you must provide the name of the creator and attribution parties, a copyright notice, a license notice, a disclaimer notice, and a link to the material. CC licenses prior to Version 4.0 also require you to provide the title of the material if supplied, and may have other slight differences.


So the easiest way to satisfy this is, indeed, to say


  Figure from reference [x], used under the terms of the Creative Commons Attribution 4.0 license.


Where your reference should contain the rest of the information, including a link. If you're pressed for space, you can abbreviate the license (CC BY 4.0), or put the text in a footnote.