[...] they are independent words rather than clitics [...]. The Eng. discourse markers, some of which have been discussed recently by James [James, Deborah, 1974, The syntax and semantics of some English interjections, University of Michigan papers in linguistics, Ann Arbor], Goldberg [Goldberg, Julia, 1980, Discourse partcles: An analysis of the role of “y’know”, “I mean”, “well”, and “actually” in conversation, Doctoral dissertation, Cambridge University], and Shourup [Shourup, Lawrence, 1983, Common discourse particles in English conversation, Ohio State University working papers in linguistics, 28, Columbus], include (certain instances of) "well, hey, okay, oh yes, like, y'know, no, uh now, say, why, look", listen, and "please" [...].
- Zwicky (2004), Pag. 372