Our Intelligent Companions, the Plants -  .

Chapter Six- Cleve Backster's Laboratory - - A chapter in a web-based book by psychologist Ingo Swann. Deals with a trip made by Swann to Backster's laboratory and chronicles the first-hand experiment he witnessed.

Dark Corner - Plants Feel - - Offers information on how plants can read human minds.

Happy Plants - - Deals with Cleve Backster's experiments and other mind/plant experiments, including ones backing up Backster.

Plant Articles by Judith Handelsman - - A series of articles from various magazines. The second one has relevance primary perception discoveries, as it describes Handelsman's own experiences with the phenomenon.

Sacrifice for Science - - Contains some information on Cleve Backster's experiments and the author's interpretations of the implications.

Vignettes From the History of Plant Morphology - - Articles about people, mostly Agnes Arber, who created unconventional theories about plant morphology.

Subtle Energy - - An article in a web-based magazine by Paul von Ward Lightworks. Deals with Cleve Backster's mind-plant discoveries and the author's speculations about them. (May 5, 1998)