Blue And Yellow Don't Make Green, by Michael Wilcox, derives its title from the common complaint that attempts to mix secondary colors, such as green, from two primary colors, in this case blue and yellow, often fail--despite common knowledge (discovered by J.C. LeBlon in 1731) that a good green should be obtainable in this way. All too frequently, the resulting mix is not the desired bright green (or orange, or violet), but a variant hue, or even a muddy brown.
The problem, Wilcox says, stems from color-bias in manufacturers' pigments. All colors are the reflections of visible light by a pigment, and all paints contain small amounts of light-reflecting pigments other than those of the color they are supposed to be. Any blue paint contains enough non-blue material to give it a slightly green or violet tint, and any yellow looks slightly green or orange. The trick to accurately mixing color is in learning, through experiment, the biases of the colors you have and then using those that will work together to give the correct result. A strong green can be mixed from blue and yellow, but only if neither color has a bias toward red.
This book is the essential reference for anyone struggling with the practical problems of mixing colored pigments in a liquid medium (the chapter which discusses other media also includes helpful information about colored pencils and pastels). Its aim is to train the student to recognize the simple differences between manufacturers' colors with confusing (sometimes deliberately misleading) names by eye, rather than by label, and to help the knowledgeable artist assemble a useful six-color palette (orange-red, violet-red, violet-blue, green-blue, green-yellow, and orange-yellow) which can be used to mix almost any color desired.
Blue And Yellow Don't Make Green (North Light Books, Pub. 1987, Rev. 1994) was invaluable to me in learning applied color theory; it is still in print and, while it is a little pricey for a thin book, it will save you the cost of a lot of bad paint choices.