Some reference platforms for educational resources, if available, are run by state authorities,
foundations or other public or private institutes; the editorial staff consists of teachers that are
engaged – full or part time – to find and evaluate educational resources they find on the net.
Other platforms rely on contributions from teachers, who voluntarily add their findings. Web
mining technologies are used to automatically extract information from contents that can be
retrieved from the net; for example, such a robot can discover automatically if a resource is
provided with a CC license.