We have the following indirect implication of form equivalence classes:
			
| Implication | Reference | 
|---|---|
| 212 \(\Rightarrow\) 94 | clear | 
| 94 \(\Rightarrow\) 34 | Non-constructive properties of the real numbers, Howard,  P. 2001, Math. Logic Quart. | 
| 34 \(\Rightarrow\) 19 | Sur les fonctions representables analytiquement, Lebesgue,  H. 1905, J. Math. Pures Appl. | 
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement | 
|---|---|
| 212: | \(C(2^{\aleph_{0}},\subseteq{\Bbb R})\): If \(R\) is a relation on \({\Bbb R}\) such that for all \(x\in{\Bbb R}\), there is a \(y\in{\Bbb R}\) such that \(x\mathrel R y\), then there is a function \(f: {\Bbb R} \rightarrow{\Bbb R}\) such that for all \(x\in{\Bbb R}\), \(x\mathrel R f(x)\). | 
| 94: | \(C(\aleph_{0},\infty,{\Bbb R})\): Every denumerable family of non-empty sets of reals has a choice function. Jech [1973b], p 148 prob 10.1. | 
| 34: | \(\aleph_{1}\) is regular. | 
| 19: | A real function is analytically representable if and only if it is in Baire's classification. G.Moore [1982], equation (2.3.1). | 
Comment: