Given the readership of this blog, there is one particular entry that may be of interest.
- Worldwide Church of God (David V. Barrett, 2013)
Of course there's more available, but the only other COG currently covered appears to be a somewhat dated and formulaic piece on the PCG (April Seabrook, revised 2001). The project has its flaws - WCG isn't yet listed in the index for example - and coverage can hardly be called comprehensive (mainline churches seem completely absent thus far). Barrett's treatment of WCG is, however, as accurate and up to date as anything else you could find about WCG in such a concise form.