Dawg is good, i learned a lot from his posts early on. The poultry health handbook has been invaluable, merecks manual, the poultry site, poultry pedia, and lots of online research papers from labs and such.
He and i strongly disagree on some key points though. Whether you are trying to make money or whether yours are pets will be the ultimate decider. His advice is geared toward commercial, advises culling in these types of cases. My approach differs in that i am not washing 5 years of breeding efforts down the drain because my birds picked up something from their environment. I prefer to breed for resistance, their chicks will be stronger than them. I was told that micoplasma chicks would be weak, sickly things but those girls were very robust. Only thing that took them out was a penchant for eating straw, which i have learned recently might be linked to needing more fiber. Mine can not simply be replaced, and if it is in my area i would just face it again down the line. I don't handle other birds without a good change and wash, no one visited my coop so it is what it is. I understand carrier status but with the exception of meraks i do not fear it.