<P> Elementary art education materials, dictionaries, and electronic search engines often define primary colors effectively as conceptual colors (generally red, yellow, and blue; or red, green, and blue) that can be used to mix "all" other colors and often go further and suggest that these conceptual colors correspond to specific hues and precise wavelengths . Such sources do not present a coherent, consistent definition of primary colors since real primaries cannot be complete . </P> <P> The perception elicited by multiple light sources co-stimulating the same area of the retina is additive, i.e., predicted via summing the spectral power distributions or tristimulus values of the individual light sources (assuming a color matching context). For example, a purple spotlight on a dark background could be matched with coincident blue and red spotlights that are both dimmer than the purple spotlight . If the intensity of the purple spotlight was doubled it could be matched by doubling the intensities of both the red and blue spotlights that matched the original purple . The principles of additive color mixing are embodied in Grassmann's laws . </P> <P> Additive mixing of coincident spot lights was applied in the experiments used to derive the CIE 1931 colorspace . The original monochromatic primaries of the (arbitrary) wavelengths of 435.8 nm (violet), 546.1 nm (green), and 700 nm (red) were used in this application due to the convenience they afforded to the experimental work . </P> <P> Red, green, and blue light are the ideal primaries for additive color mixing since primary lights with those hues provide the largest triangular chromaticity gamuts . Small red, green, and blue elements in electronic displays mix additively from an appropriate viewing distance to synthesize compelling colored images . </P>

Which of the following are examples of primary sources (select all that apply)