Question: What year did the Rembrandt Research Project begin?
About the article "Rembrandt", section "Expert assessments".

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The Rembrandt Research Project (RPP) is an initiative of the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), which is the Netherlands Organization for Scientific Research.
Its purpose is to organize and categorize research on Rembrandt, with the aim of discovering new facts about this Dutch Golden Age painter and his studio.
The project was started in 1968, but has since become the authority on Rembrandt and has final say in whether a painting is "genuine". 
The following is a list of paintings by Rembrandt that are generally accepted as autograph by the Rembrandt Research Project and other sources.
Note that this list is not authorized by the Rembrandt Research Project, and that Ernst van de Wetering, Director of the Project, is currently preparing an illustrated survey of Rembrandt's painted oeuvre.  
Out of the Shadows is a 2012 documentary produced by Sullivan Entertainment.
The documentary features Dr. Joris Dik as he works toward re-attributing ‘Portrait of an Old Man with a Beard’ as a Rembrandt painting.
The results of the process documented in the film were announced on December 2, 2011 as the Rembrandt Research Project classified the ‘Old Man’ as a Rembrandt.
The film is narrated by Donald Sutherland. 
The first registration documenting the work and the authorship of Rembrandt dates back to the 17th century.
The portrait in São Paulo Museum of Art was reproduced in a work by Ferdinand Bol, a direct student of Rembrandt.
At least three eighteenth century prints of the work were also produced: one from Pieter van Bleek, another from Murray and a third from Johann Georg Hertel II.
All three bear the inscription "Rembrandt pinxit" ("Rembrandt painted it").
In the historiography, the portrait appears in biographies, compilations and catalogues of Rembrandt paintings since at least 1822.
There are many references to the canvas as being one of the painter’s masterpieces (John Smith, 1836; Carel Vosmaer, 1877, amongst others), also it is certified by a considerable number of old copies and depictions produced by other renowned artists such as William Hogarth.
In 1968, Gerson noted that the accreditation to Rembrandt ""is not totally convincing"” and in 1983 Sumovsky put forward the name Govaert Flinck as a possible painter of the portrait.
But it was only in 1989 that an opinion contradictory to the traditional accreditation was formed.
In that year, the work was analysed by a member of the Rembrandt Research Project, a committee of specialists based in the Netherlands, to determine the authenticity of all the known paintings of Rembrandt.
The Commission’s judgement was to deny the accreditation to the Dutch master, attributing the work instead to the “Rembrandt circle”.
A polemic discussion was established.
In the same year, the historian Pietro Maria Bardi declared his disagreement with the Commission’s decision.
Three years later, he restated his belief that the portrait "is a masterpiece", pointing out that many "foreign museums refuse to believe the Commissions verdict".
In fact, institutions such as the Frick Collection of New York, and specialists such as Simon Schama have rejected the Committee’s decision and the Rembrandt Commission have revised many of their accreditations (in 2005, four paintings attributed to the "Rembrandt circle” were republished by the Commission as Rembrandt’s autographic works).
In 1998, Luiz Marques, Professor of Art History at Unicamp, also disagreed with the Commission’s judgement, listing a series of elements disregarded in the analysis by the Committee that, in his opinion, “distances the work from the radius of the Rembrandt action” Marques even observed that scientific examination is necessary to obtain a more specific analysis surrounding the accreditation of the portrait, and the true authenticity of the signature – ignored by the Commission -, remembering that the prestige that the portrait enjoyed in the past also is a strong indication of its origin, at least in the Rembrandt studio.
Besides the above, the work was attributed to Rembrandt with more or less conviction by Hofstede de Groot, Abraham Bredius, Van Gelder, Haverkamp-Begemann and Christopher Brown amongst others, and by all the specialised critics prior to the 20th century, with the exception of Waagen. 
As a result of the project, which analyzed documentation, techniques, and forensic research on Rembrandt paintings from his early years in Leiden until his death, the number of signed Rembrandt "self-portraits" around the world has been reduced by half.
Also, more paintings have been attributed to students working in the Rembrandt studio, and more has been discovered about the ways in which the students worked.
Recently, period copies of Rembrandt paintings are being studied for clues as to whether certain copies were factory-style pieces for visiting functionaries.
Rembrandt's work was in high demand for decades, and he managed to keep productivity up while also keeping his prices high by enforcing strict quality control on the work done in his studio.
The project's five-volume publication, "A Corpus of Rembrandt Paintings", is considered the definitive authority by all auction houses and dealers who work with works by Rembrandt and his studio.
The research project has proved invaluable to art historians, and the lack of such a project for other prominent Dutch painters such as Frans Hals is felt sorely by museums and collectors trying to acquire the same sort of "stamp of approval" on their paintings.
However, the project has also initiated debate about the feasibility of conclusive attribution, particularly for painters who were associated with one or more workshops.