Hello everyone. I like to ask for suggestions for an efficient reference manager software. Hm, here are the characteristics I am looking for. -Has an online counterpart where I can save articles that I want to download someday -Has a tagging system (i.e. I can attach certain keywords to an article and when I type that keyword, all articles that is attached to that keyword will appear) -Has annotations system for writing notes in the journal articles I read. Preferably something that allows me to highlight the text in the PDF. -Transferable data (i.e. if I choose change the Reference Manager Software, I could export my data in some popular format and input that to my new software.) I checked online and there are a lot of suggestions such as Mendeley, Zotero, Docear, etc. What software do you recommend to use? Thank you very much.