I am trying to pin down: who first proved that $WKL_0$$\mathsf{WKL}_0$ has an $\omega$-model in which every set is of low degree? As shown in Simpson's Subsystems of Second Order Arithmetic (Theorem IX.2.17), one doesn't have to travel too far to get to this result when starting from the low basis theorem of Jockusch and Soare. But Simpson's typically extensive bibliographic remarks on the section in which this result is proved offer no indication of when this fact about $WKL_0$$\mathsf{WKL}_0$ was first noted. Thanks.