When you are surfing on the Internet, you might find documents, information, etc. on Phosphenism, do keep a certain reserve and be careful not to practice what is on offer.
Almost all those documents are misleading. As it is the case with prescription drugs, there are certain mixtures of techniques that it is better to avoid.
Above, you will find a list of genuine sites on Phosphenism.

Internet warning: 90% of the Internet users take their site, their blog, or forums for a therapy and pour out their neuroses, phobias, and paranoia in them. It is an image of the
disorders of our society…
Therefore, it is advisable to be careful and respect 2 rules:

1 - Refer first of all to the official site,
2 - Be very prudent and on your guard when it come to other written documents.

Dr Lefebure, in virtue of the content of his works, aimed at rather high level, which preserves us from most of the neuroses which tend to be found in practices other than Phosphenism.

To all, thank you for your help and support.

Check: How can I spread the word on Phosphenism