Possible to find DOI number from article that’s on PubMed but doesn’t list one.

I’m looking for this article “[A new and novel treatment of opioid dependence: Nigella sativa 500 mg](https://pubmed.ncbi.nlm.nih.gov/19385474/)” The study is from 2008 so it’s not ahead of print. But, when I try and search using the URL or the PMID (19385474) it comes back with nothing. I feel like if I had the DOI number I could get it.

Also, these mirrors are looking a little sketchy. A lot of them kick me to sci-hub.ru.

Any help would be appreciated!