Eww, read the Opening post again, haha, ASW is used there as Apparent Stage Width.
Sorry contributing to confusion not being fully aware on the opening post but thinking and pushing my own stuff.
Sorry OP, I've got no collection of papers to link to, and can only provide what I have been observing from papers and with my setup and it seems that there is lot of confusion about it all reading the first post.
Stereo image has various qualities that depend on various things. Even though you had ideal speakers dropped from outerspace with ideal response some scientist found out, still you room and the speaker and listener position would still affect all stereo image qualities. And to sort that out, how to position things, you must know which one you want to hear: "near field" sound where you hear mostly spatial effects from the recording, or "far field" sound where sound of the recording is strongly influenced by your room and they fuse into one perception.
Main objective for main speaker is to have uniform directivity in a way, that it allows you to rotate the speaker solely to affect early reflections in the room, so nice DI. This allows maximum flexibility trying to find good positioning. If there is only one good listening axis you cannot change toe-in, if it ruins direct sound, which prevents you using toe-in adjusting the room sound. In addition, you'd want to have separate bass system, tha allows you to adjust that independently of the two main stereo speakers, agaib due to effects of room. Bass has great spatial effect as well, so it's must to be able to adjust it witgout touching main speakers, if you want best stereo sound in room.
You could also get rid of the room, but that would prevent spaciousness and envelopment.
Key is to position the set in room so that sound you are after happens. You need to know what perceptiom you are after, and suitable loudspeakers that enable you to have it in the room you happen to be in.
I think I started posting here to promote you must know how to listen and what to listen, in order to have any use of the knowledge in the papers. Nobody on this forum, or the papers can achieve the end goal for you, you must do it yourself, the listening.
I hope it helps!
have fun listening your stereo!