There's nothing to research. There's a four-year gap in the DS9 narrative between the events of The Soul Key and Rough Beasts of Empire. RBoE was the book that first revealed the events of that interval to us in retrospect -- kind of like the way ST:TMP began with Kirk already an admiral, Spock almost completing Kolinahr, McCoy as a bearded hermit, etc., or the way TUC began with Sulu already completing his third year as Excelsior captain. As with those things, maybe someday we'll get flashback tales filling in the gap, but to date all we have are the books picking up after the gap, i.e. the loose trilogy of RBoE, Plagues of Night, and Raise the Dawn.
Thanks for clarifying! It's an interesting change!
You may feel differently after reading PoN/RtD.
*eagerly goes to download them on his Kindle*
Thanks for taking time out from your schedule to keep your fans informed, Christopher. We appreciate it.