I am trying to pin down: who first proved that [$\mathsf{WKL}_0$][1] has an $\omega$-model in which every set is of [low degree][2]? 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][3] 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 $\mathsf{WKL}_0$ was first noted. Thanks.


  [1]: http://en.wikipedia.org/wiki/Reverse_mathematics#Weak_K.C3.B6nig.27s_lemma_WKL0
  [2]: http://en.wikipedia.org/wiki/Low_%28computability%29
  [3]: http://en.wikipedia.org/wiki/Low_basis_theorem