Unfortunately, I don't know too much about replacement CFL, plug-in lamps. I am having trouble finding a summary. I'd like to know if all bulbs that fit will work with any possible ballast.

I am visiting my father-in-law and he wants to find some back-up replacements for three of his lamps.

2 are OTT lite. They seem to need a 13W, U-tube lamp with two pins. One says 13W PL

The other is another manufacturer and the lamp appears to accept a "PL/F 27W PL/F", 4-pin lamp as quoted from the lamp base. The lamp itself is marked, "27WKFDL27EX-cw"