- Idealism (plato.standford.edu)
This entry discusses philosophical idealism as a movement chiefly in the eighteenth and nineteenth centuries, although anticipated by certain aspects of seventeenth century philosophy and continuing into the twentieth century.
- Real number (Wikipedia)
In mathematics, a real number is a number that can be used to measure a continuous one-dimensional quantity such as a distance, duration or temperature. Here, continuous means that pairs of values can have arbitrarily small differences. Every real number can be almost uniquely represented by an infinite decimal expansion.