I have to cite a product manual in a journal paper, but the product manual do not have a year mentioned on it. The content of product manual has not changes over the years. Could this type of documents be cited in a paper or thesis?

If you have not seen a manual like this, then this is an example: https://www.specmeters.com/assets/1/22/6460_SM1002.pdf

  • 3
    The meta data of the file (view the file properties in Acrobat Reader) shows that it was created/last changed in 2014.
    – user9482
    Jun 14, 2018 at 7:45
  • 1
    The last page says "3/14" which matches the file properties as @Roland says.
    – mkennedy
    Jun 14, 2018 at 21:11

2 Answers 2


First, if this is a student paper, ask your supervisor; if it's a journal article or similar publication, consult the style-sheet.

I've seen 'n.d.' for 'no date'. For online sources, it's a good idea to include the last access date, like so:

Brown, Alice (n.d.), On the Flubbication of Foobars, Report, Institute for the Study of Things, Boulder, Co., http://thingsistitute/pub/flubbication.pdf (accessed 6 June 2018).

  • 5
    For a manual I would include any version number available for the software or product.
    – user9482
    Jun 14, 2018 at 7:46

I'm quite surprised that the manual does not provide a date - but indeed, it does not (checked your link, what was the manufacturer thinking?).

In terms of a practical solution, you could accompany your reference with the date you accessed the manual (like a webpage) if you use the online link or maybe the purchase/production year/revision number if you refer to the printed copy that came with the device.

And there is always the option of omitting the year, if it truly cannot be determined. But giving the reader an idea of when it was obtained may nevertheless prove beneficial. (The paper date would not be a good indication as in some cases, laboratory equipment can be decades old. So there is no obvious way to infer the age of equipment for the reader.)

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