Beyond these well known systems there are many other research oriented prototype systems which represent the research effort for the development of third generation hypermedia systems. Some of them are especially well documented such as aTrellis and ExperText. Dexter model is another well documented hypermedia reference model. Prototype systems like DeVise and Amsterdam hypermedia are based in Dexter model. Canto, Nested Context Model, HyperSet, InterSect, HyperNet are hypermedia models and prototype systems aiming in eliminating hypermedia problems by providing more elaborate structuring mechanism than the simple graph-based hypertext model, composites entities.
Harmony is a prototype hypermedia system which is based in object oriented paradigm.
World Wide Web is another hypermedia system which was developed to be a pool of human knowledge, which would allow collaborators in remote sites to share their ideas.