There was a pretty good article in Audiohlics fifteen years ago.
https://www.audioholics.com/subwoofer-setup/subwoofer-placement-the-place-for-bass-part-1
The rectangular solid images you see on the 1st page, showing how sound pressure peak values are different for different parts of the room, will play with your brain until you correctly sort out which of the two possible 3-D interpretations is the correct one. The box has one vertical corner at the top of the image and one vertical corner at the bottom of the image. You are looking into the box and seeing one of these corners as an interior vertical corner. The other one is effectively an exterior vertical corner. If you can consciously force your brain to see the upper vertical corner as an interior corner, that you see when looking the box, it will then make visual sense. But not if you see it the other way.
Down at the bottom of the page there is a drop-down scroll box for selecting the next page to "jump to". If you don't manage this selection you can end up taking a sort of random walk through the various pages, and it will be confusing. The pages I found most interesting are the ones dealing with dual sub placement.
According to the simulations presented, the best dual-sub placements are at the midpoints of opposing walls. The front/back wall alternative seems better than the side walls. The two front corners are not great but neither is this configuration particularly bad. Ditto for placement near the L&R main speakers.
My sense is that there is an inherent conflict between optimal location for mitigating room modes vs. placement where you won't always have the sense that the bass is coming from somewhere besides the main speakers. Different people seem to have a different sense of what does or does not constitute proper integration of the main speakers with the subs. An option not often given the consideration that is deserved is the use of main stereo speakers with deep bass capability augmented with a single high-quality subwoofer located at the rear wall. If the subwoofer located at the rear wall is capable of truly deep bass, down to 20 Hz or close to it, and if the crossover point between it and the main stereo speakers is in the vicinity of about 50 Hz, then because of the overlap, the main stereo speakers will provide useful output down close to 20 Hz, and the big subwoofer in the back will provide useful overlap up to 100 Hz or higher depending on the steepness of the LP filter. Thus, through most of the low-bass and mid-bass frequencies you actually have three subwoofers, two located at the front wall and potentially near the front corners, and one in the back. There can be little doubt that this is an
exceedingly good arrangement from the standpoint of mitigation of room modes. And with this arrangement there is no issue with integration of the main speakers with the subwoofer. This may well be the
only arrangement that appreciably avoids the compromise between the two conflicting needs. The only way to get this arrangement without a kludgy hookup of subwoofers to the main speaker wiring is with main stereo speakers that have true deep bass capability. Sealed (acoustic suspension) speakers are desirable so long as the F3 point is below about 40 Hz. Ported speakers are good so long as the port tuning is similarly low (which is necessary because of the steep rolloff), which generally implies large floor-standing ported speakers. As someone who owned a pair of Advent 5012 (the last before Jensen took over and replaced the woofer with one of their cheaper commodity woofers), I know from personal experience that a pair of acoustic suspension speakers of this type, augmented with a single high-quality subwoofer located at the rear wall, leaves little to be desired for anyone whose objectives include not spending the cost of an automobile on a home audio setup.