Sir

Why are patent citations so conspicuously absent across academic journals, with most even omitting formatting instructions for these in their author guidelines? Patents present novel, rigorously reviewed unpublished work, as well as providing an unmatched resource for detail.

We randomly selected one month (December 2008) and reviewed all citations in the reviews, articles and letters/reports in Nature (1,773 citations) and Science (1,367). These citations included textbooks, http://arXiv.org preprints and abstracts — but no patents.

The lack of cited patents may come about partly because authors find academic papers more readable, or perhaps because the work reported and discussed in academic journals is not being commercialized. However, the scientific data within some patents may appear in abbreviated form in subsequent academic publications.

In 2008, the US Patent Office issued 185,246 patents. In the past, the patent literature has been difficult to search, but this is no longer the case. Matters have improved with the introduction of services such as Espacenet (http://ec.espacenet.com) from the European Patent Office, which is able to search more than 60 million patent publications worldwide, and Google Patents (http://www.google.com/patents), a free search engine indexing more than 7 million patents from the US Patent Office. Searches can also be undertaken at the US Patent and Trademark Office (http://www.uspto.gov) and the World Intellectual Property Organization (http://www.wipo.int).

These advances mean that there should now be a more comprehensive citation of the patent literature in scientific publications.