Another study, this time by Maastricht University in the Netherlands. Only a short one about 5 min long...
"We are looking for any and all individuals who have ever used a psychedelic (including MDMA). If this is you, we kindly ask you to fill out our 5 minute questionnaire, so that science can benefit from your experience! The questionnaire is completely anonymous and confidential.
For more information, you can follow this link to the survey: https://maastrichtuniversity.eu.qualtrics.com/jfe/form/SV_cNr4SHEEidiUBMN
"