It seems "Everyone" knows they're highly disruptive for many situations but often times clients don't. Particularly in desktop applications this form of dialog is often misused, often disrupting a workflow.
I intellectually know all of the reasons to avoid them and some rare cases they may be warranted, and we have a great deal of anecdotal evidence and professional opinions in our modal-dialog questions.
I know there is published research on modal dialogs, but to my dismay few people reference this research when supporting or opposing the use of modals dialogs.
I know for example that distracting users while in a state of flow (such as writing an essay in Microsoft Word) can be easily destroyed by interruptions such as modal dialogs, having disastrous results on productivity.
In my particular case the issue is attention (working on the mistaken opinion that modal dialogs attract attention and comprehension) and productivity as the dialog disrupts workflow for a "confirmation".
What are the most convincing resources to give to a client who believes modal dialogs are not problematic?
I am particularly looking for scholarly articles, but high level explanations (which cite real data) may be applicable as well.
Wikipedia has a good list of "common knowledge" about and criticisms of modal windows, but even they mostly cite blog posts and a couple books.