Wikipedia:Scientific citation guidelines
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consensus. When in doubt, discuss first on the talk page.
The no original research and verifiability policies are of paramount importance to Wikipedia. Inline citations, which link specific reliable sources with specific pieces of information in the article, provide practical support for these policies by making it possible for readers to verify the article content.
This page applies the advice in the policies, and in the citing sources guideline, to referencing science and mathematics articles. The goal is to achieve a reasonable balance between ease of verification, readability and editability. This page also describes some sensible guidelines for dealing with issues that are specific to writing Wikipedia articles (compared to writing for the academic press).
Some statements are uncontroversial and widely known among people familiar with a discipline. Such facts may be taught in university courses, found in textbooks, or contained in multiple references in the research literature (most importantly in review articles). Some examples are:
- Galilean relativity with the postulate that all observers will always measure the speed of lightto be the same no matter what their state of uniform linear motion is.
- A frustrated spin glass may have a large ground state degeneracy.
- type IIBsuperstring theory.
These statements are not common knowledge, but the first should be known to anyone with an undergraduate background in physics, the second to anyone knowledgeable about condensed matter physics, and the third to anyone knowledgeable about string theory.
The verifiability criteria require that such statements be sourced so that in principle anyone can verify them. However, in many articles it is cumbersome to provide an in-line reference for every statement. In addition, such dense referencing can obscure the logical interdependence of statements. Therefore, in sections or articles that present well-known and uncontroversial information – information that is readily available in most common and obvious books on the subject – it is acceptable to give an inline citation for one or two authoritative sources (and possibly a more accessible source, if one is available) in such a way as to indicate that these sources can be checked to verify statements for which no other in-line citation is provided. These inline citations are often inserted either after the first sentence of a paragraph or after the last sentence of the paragraph; a single convention should be chosen for each article.
For example, from aldol reaction:
The aldol reaction is an importantα,β-unsaturated ketone(or aldehyde).
The enol or enolate is itself generated from acarbonyl compound, often an aldehyde or ketone, using acid or base. If the enol or enolate is formed in situ, the process can be considered as an acid or base-catalyzed reaction of one carbonyl compound with another. This may involve one aldehyde or ketone reacting with itself. Alternatively two different carbonyl compounds may be used, in which case the reaction is known as a crossed aldol reaction. In the scheme shown, the enol or enolate of a methyl ketone reacts with an aldehyde.
- ISBN 013187151X
- ISBN 0-471-58589-0
- ISBN 3-527-30714-1.
- ISBN 0080405932. (Review)
- ISBN 0471861413. (Review)
Five references are provided early on: two textbooks, a specialized monograph on aldol reactions, and two review articles. Most readers would assume that the bulk of the statements in the comparatively short Wikipedia article could be verified by checking any of these references, and so it may only be necessary to provide additional in-line references for controversial statements, for recent discoveries that are not covered in the standard references, for historical and academic attribution, and for verifying more specialized statements or subsections.
When quoting widely known numbers such as the
Articles without in-line references
Sometimes, short articles (including many stubs) provide a list of references without any inline citations. This can satisfy the sourcing policies when the entire contents of the article can be verified from the sources listed. An example of a very short article covered by
As an article matures to include more than a few sentences, inline citations are added to make it clear which material in the article can be verified by which source. If a few general references cover the bulk of an article, consider using the technique described in the section Uncontroversial knowledge above. This can be done regardless of article length.
Some material, including direct quotations, contentious material about living people, and any material whose verifiability has been challenged, should always be accompanied by an inline citation, regardless of the length of the article. For more information on these special cases, see
For some topics the bibliography available may address different audiences, e.g. undergraduate vs. graduate, or levels or rigor, e.g. statistics textbooks for social scientists vs. those addressed to mathematicians. When the audience of a text in the further reading section is not self-evident, it may be useful to annotate it as discussed at
Examples, derivations, and restatements
Wikipedia is neither a textbook nor a journal. Nonetheless, in mathematics and the mathematical sciences, it is frequently helpful to quote theorems, include simple derivations, and provide illustrative examples. For reasons of notation, clarity, consistency, or simplicity it is often necessary to state things in a slightly different way than they are stated in the references, to provide a different derivation, or to provide an example. This is standard practice in journals, and does not make any claim of novelty.
Wikipedia's no-original-research policy allows
If a calculation, although routine, takes more than one or two steps, it may be helpful to present the details of the calculation in a note to the text. For an example, see the detailed calculation in the article on Methane clathrate giving a derivation of the statement in the article's lead that one liter of methane clathrate solid at STP contains, on average, 168 liters of methane gas.
Wikipedia's no original research policy requires that we make it clear assertions do not originate with Wikipedia's editors. This is achieved by providing sources for the material in Wikipedia articles. It is also important, however, for our articles to clearly indicate the person who first discovered an astronomical object, first proved a theorem, first performed an experiment, or was otherwise responsible for the idea being discussed. The process of giving credit to the original discoverer will be called attribution here.
Articles should provide attribution for experiments, theorems, astronomical objects, and similar topics, when the original discoverer is known. Many editors prefer to supply the original source for an idea when providing this attribution, for example:
- Supernova 1987A was discovered by Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile on February 24, 1987, and independently by Albert Jones in New Zealand.
- Kervaire and Milnor showed that the oriented 7-sphere has 28 different smooth structures (or 15 ignoring orientations), and in higher dimensions there are usually many different smooth structures on a sphere. (from Poincaré conjecture)
When the original reference is not suitable as an introduction to the idea, either because it is outdated or because it contains serious errors, it is helpful to note this in an annotation:
- Beginning with observations in 1912,
Numerical data can also be attributed to the person or group that obtained it. For example, from the neutrino article:
- The strongest upper limit on the masses of neutrinos comes from electron volts.
This provides attribution for academic and historical purposes, and also makes it clear how readers can understand where a number comes from. This not only makes Wikipedia a more convenient resource for readers, but makes it easier to update when better data become available.
A related issue is the attribution of eponyms (terms derived from people's names) such as:
- ...the Michelson–Morley experiment...
- ...the Sunyaev–Zel'dovich effect...
- ...the Green–Schwarz anomaly cancellation mechanism...
- ...the αβγ neutron capture theory...
- ...the Kaluza–Klein theory of dimensional reduction...
If Wikipedia has an article about an eponymous topic – such as
- Wikipedia:Manual of Style (mathematics)
- Wikipedia:Manual of Style (Medicine-related articles)
- Wikipedia:WikiProject Chemicals/Style guidelines (very out of date on citations!)
- Wikipedia:Citing sources
- Wikipedia:No original research
- Wikipedia:Citation templates
- Wikipedia:Manual of Style (summary style)#References, citations and external links
- WebCite – tool to archive webpages to allow stable citation links.
- ^ See Manifold Destiny for a possible counterexample.
- ^ D. N. Spergel; et al. (WMAP collaboration) (2013). "Bibliography of WMAP Science Team Publications".
- JSTOR 1970128.. This paper calculates the structure of the group of smooth structures on an n-sphere for n > 4.
- Lowell Observatory Bulletin, pp.2.56–2.57 . His article entitled "The radial velocity of the Andromeda Nebula" reports making the first Doppler measurement on September 17, 1912. In his report Slipher writes: "The magnitude of this velocity, which is the greatest hitherto observed, raises the question whether the velocity-like displacement might not be due to some other cause, but I believe we have at present no other interpretation for it." Three years later, in the journal Popular Astronomy, Vol. 23, pp. 21–24 , Slipher wrote a review entitled "Spectrographic Observations of Nebulae". In it he states, "The early discovery that the great Andromeda spiral had the quite exceptional velocity of −300 km(/s) showed the means then available, capable of investigating not only the spectra of the spirals but their velocities as well." Slipher reported the velocities for 15 spiral nebulae spread across the entire celestial sphere, all but three having observable "positive" (that is recessional) velocities.
- S2CID 119535760.
- OCLC 25799867.
- S2CID 117050217.
- ^ Nordström, Gunnar (1914). "Uber die Möglichkeit, das elektromagnetische Feld und das Gravitationsfeld zu vereinigen" [On the possibility of a unification of the electromagnetic and gravitational fields] (PDF). Physikalische Zeitschrift. 15: 504–506.
- ^ Kaluza, Theodor (1921). "On the problem of unity in physics". Sitzungsberichte der Preussischen Akademie der Wissenschaften: 966–972.
- Dodelson, Scott (2003). Modern Cosmology. ISBN 0-12-219141-2.
- Hu, Wayne; Dodelson, Scott (2002). "Cosmic microwave background anisotropies". S2CID 569887.
- Kolb, Edward; Turner, Michael (1988). The Early Universe. ISBN 0-201-11604-9.
- Liddle, Andrew; Lyth, David (2000). Cosmological Inflation and Large-Scale Structure. ISBN 0-521-57598-2.
- Mukhanov, Viatcheslav (2005). Physical Foundations of Cosmology. ISBN 0-521-56398-4.
- Peebles, Phillip James Edwin (1993). Principles of Physical Cosmology. ISBN 0-691-01933-9.