I don't know of any sources. They're my personal friends. Met them at parties smoking dope. Some of the loosest people I know in terms of cannabis and yet they're top in the state and the country for their overall grades. In Australia we have what's called the ATAR, the Australian Tertiary Admissions Ranking. Not a mark, but a ranking system to find out how you compare against other students. Kind of like the LSAT for law schools in Europe and North America. You can find the ATAR results either online or on most newspapers. For example, the top in the state for English in the 2014 school year, my good friend Toby Wilcox, is one of the biggest pot heads I know. A good friend of mine as well, who is currently doing his high school diploma, is the captain of the debating team that has won the national championships 3 years in a row. Although he hasn't attained his marks yet, his trial marks put his ATAR score in the top .5% of the state. This guy has done every drug I know of apart from heroin and methamphetamine. He's done LSD, speed, mdma, ecstasy, cocaine, dom, shrooms, dmt, dxm, codeine, ketamine etc etc. And cannabis of course. He just turned 18 about a week ago and has been doing these drugs since he was 15 years old. He is living proof that drugs do not cause any form of serious harm to the intellect of young adults. He is living proof that drugs in fact cause the opposite. If any such research were to be done on the effects of cannabis in the young mind, one of the biggest problems that anti drug people would face would be people like my friend who have excelled in school through drug use.