I have a database of references for my site, many of the references in there are pubmed, but some many of them are from other journals. I need a way to automatically convert the URL of studies from different journals into a DOI. I also need to get the abstract from them. I have this firefox plugin called zotero, you enter the link of a journal and it automacally gets the metadata for you so theres clearly a way to do this but I don't know how they do it. With pubmed articles its easy because they have an API, and they have their PMID in the URL. But I don't know what to do with articles from other journals.