The Internet Archive discovers and captures web pages through many different web crawls.
At any given time several distinct crawls are running, some for months, and some every day or longer.
View the web archive through the Wayback Machine.
For exact values of to and 40S values of to ,
see Char (1980). Also see Cuyt et al. (2008, pp. 223–228),
Jones and Thron (1980, pp. 348–350), and
Lorentzen and Waadeland (1992, pp. 221–224) for further information.