Here are a few useful Internet sites not mentioned in other places in this information system. Citing Internet resources is problematic because some of them may be transitory. To help assure your being able to access these sites, we have attempted to provide two sites for each item. Generally one is the direct link and one is the link to the parent organization or element, assuming that the parent will be more stable. For example, the Society of Wetland Scientists is unlikely to change its Web address, but those of its secondary links could change over time.