If possible please include possible references for additional research and information.
First, distance learning includes any education that takes place from a distance, and this includes correspondence courses which are traditional mail based, lessons received via television, cable or closed-circuit television, short-wave radio, or via any other transmission method imaginable, including what most of us modern students consider the norm when we hear that term: lessons or courses delivered via the World Wide Web using a computer.
Some of my favorite resources, APA 6th edition formatted, in no particular order:
Rosenberg, M. J. (2001). e-Learning: Strategies for delivering knowledge in the digital age. McGraw-Hill: New York.
Maeroff, G. I. (2003). A classroom of one: How online learning is changing our schools and colleges. Palgrave Macmillan: New York
Levine, S. J. (2005). Making distance education work: understanding learning and learners at a distance. Learner Associates.net: Okemos, MI.
Grabe, M. & Grabe, C. (2007). Integrating technology for meaningful learning. Houghton Mifflin: Boston, MA.
Palloff, R. M. & Pratt, K. (2001). Lessons from the cyberspace classroom: The realities of online teaching. Jossey-Bass: San Francisco.
Palloff, R. M. & Pratt, K. (2003). The virtual student: A profile and guide to working with online learners. Jossey-Bass: San Francisco.
As to your first question, about distance learning providing the same quality of instruction as traditional education. "It would seem obvious that when students are satisfied with their online courses and programs, they are more ...
Discussion of the advantages and disadvantages of distance learning for special needs students and others, with references and Web sites.