Some are listed, some are not. I was just looking at a series of stamps from Manama - Scott and Gibbons did not list these, though Michels did. Same goes for another series I looked at from Equatorial Guinea.
I don't have any world-wide catalogues, and the only reason I found out about these particular examples was by the honesty of the person who put them on line.
If you wish to reference the series I just referred to, they are Michel #972-979
for the Equatorial Guinea, and Michel #213-219 for the Manama. Sadly there is not always an easy answer to the question "is this stamp legitimate?"
Seemingly, the only way to avoid this
particular scam is to be very sceptical about certain stamp issuing countries, and try to focus on eras that pre-date the 1970's.
That said, you will run into forgeries in any era, but that's another story.http://www.postbeeld.com/en/fsc/home/
offers an explanation as to why they have decided to omit some countries from their listings.