Example of the INTEGRAL spectrum of GX 304 − 1 (revolution 1132) with a simultaneous fit of data from JEM-X, ISGRI, and SPI with a power-law/cutoff model including a cyclotron absorption line (see text) a); the residuals for a fit with the model without the cyclotron line for JEM-X + ISGRI b); and JEM-X + SPI c); and with the model where the line is included for data from all instruments d).