How to cite my own submitted but not yet published work? I plan to submit part of my current work to conference A. I then wish to submit my whole work to a more prestigious conference B. As for the part submitted to A, there is no point of repeating it again. So I will just cite my submission to A in my submission to B. 

But the problem is that the submission deadlines for A and B are roughly the same. So actually the moment I submit the work to B, my partial work submitted to A has not been published yet. I have not even been notified of its acceptance.

Can I still cite it? My concern is that even if I can cite it, one will find nothing online.
In principle you can cite other, submitted work in a research paper. Just give the authors, paper title, and either "Submitted." or "Submitted to [venue]." in the reference list.

However, both as a reviewer and reader, I usually find this disappointing. I already came across several cases where I wasn't able to find the cited paper even years after publication of the paper with the citation. It is well possible that the cited paper is rejected, and maybe someone just doesn't follow up to really get it published. As a better alternative, check whether you can put a preprint version of the paper you want to cite online (e.g. on arxiv), and just cite that.