Working papers are usually pre-publication versions of academic journal articles, which have already been submitted, or are in the process of being submitted for publication.
Working papers are available online, often as part of a working paper series. The main purpose of these documents is to disseminate information, and present new research findings.
Working papers are not refereed. In fact, by posting the document online, the author may receive feedback, which could help improve the publication.
The content of the working paper is usually the responsibility of the individual author(s), and they will include their email address for commnents and feedback.
You can refer to working papers when you are writing your assignment or your dissertation. Once the working paper has been published, you should cite the document in its final version, as published in the academic journal.