Q. I need primary sources on the drug ibogaine, where should I look?

Try

1. Elsevier Science Direct, search ibogaine for very good returns 
2. JSTOR also good returns for ibogaine AND addiction 
3. Google scholar, most sweeping, so use many keywords for example:  ibogaine and addiction and heroin treatment

Primary sources on this drug [ibogaine] included:

• research
• clinical trials
• findings and conclusions reported by scientists in reputable medical journal
• conference proceedings discussing this drug ibogaine [2009 drug policy alliance conference]

Consider locating a literature review on Ibogaine  and search names of scientists who are proven in the ibogaine research field (metaphor would be to grow the "pearl" listed in the literature review).