Retrieving the references in a publication automatically This is probably not 100% on-topic here, but this site is closer to appropriate than others. Let me give it a try: I have collected about 50 publications relevant for a project of mine. For these publications, I have all the important information like author, title, journal, etc, but most importantly, I have the DOI for each paper. 

I was asking myself, is it possible to retrieve the DOI of the references given in each publication through a web-service, an open database or any other service?

Background is that I would like to create a graph showing the connections between the selected publications. One semi-automatic approach which comes to my mind is to use Web of Science, go through the stack of my publications and copy the DOI of the listed references.

Any better ideas?
Both Scopus and Web of Knowledge contain all the information that you need and have APIs that can be used to automate access:


http://info.sciencedirect.com/scopus/scopus-in-detail/tools/api
http://wokinfo.com/products_tools/products/related/webservices/


I have never used them personally, but I hope this kind of information can be accessed using them. Each site indexes articles with their own unique key, so you can use those instead of DOIs if you only need them as unique keys.

Neither of them is free; you can probably access them through your university's subscription though. Be sure to check the usage limits.