1920-S? Era Stamp Book (Determining ##, 554?)

Quarantine is a funny thing...I find myself looking back at the old stamp collection that I haven't pulled out for several years.
My question is how to figure out the Scott number for a book of stamps (pictured). The sheets vs. coils have different numbers, and these would have only one side perforated, but I don't see a distinction in my reference materials (which are very old and crappy to be honest). #554 seems to have more perforations (like this one) compared to 583 or 606.

I think I might have figured it out. "b" after the Scott number?

Not my area but it looks like you have a 4th Bureau booklet of 4 booklet panes. A quick perusal of my Scott U. S. Specialized catalog yields the following possibilities:
554c flat plate perf 11 booklet panes in booklet BK70
583a rotary press perf 10 booklet panes in booklet BK73
634d rotary press perf 11x10.5 booklet panes in booklet BK81
Someone with a lot more knowledge than me in this area will be needed to sort it out from there.
NOTE: Scott does not list the individual booklet stamps, just the panes and complete booklets.

583 is perf 10 … this stamp is perf 11 or perf 11x10.5. So it can't be 583. 606 is a perf 10 coil & was not issued in booklets … so it's not 606. This leaves 554 or 634. 554 is flat plate perf 11, 634 is rotary perf 11x10.5. Perf measurement might be simplest way to determine which it is. Booklet stamps were not given separate catalogue numbers … but the panes of 6 were. The pane is either 554c or 634d.

Thanks so much to everyone who responded so quickly to my post. I don't have a perforation gauge, but I was able to line it up with another stamp that was only issued 11 x 10 1/2. I guess that means 634d is likely the correct identifier.