We have the following indirect implication of form equivalence classes:
			
| Implication | Reference | 
|---|---|
| 259 \(\Rightarrow\) 260 | 
							 	Variations of Zorn's lemma, principles of cofinality, and Hausdorff's maximal principle, Part I and II, Harper,  J. 1976, Notre Dame J. Formal Logic  | 
					
| 260 \(\Rightarrow\) 40 | 
							 	Variations of Zorn's lemma, principles of cofinality, and Hausdorff's maximal principle, Part I and II, Harper,  J. 1976, Notre Dame J. Formal Logic  | 
					
| 40 \(\Rightarrow\) 39 | clear | 
| 39 \(\Rightarrow\) 8 | clear | 
| 8 \(\Rightarrow\) 27 | clear | 
| 27 \(\Rightarrow\) 31 | clear | 
| 31 \(\Rightarrow\) 32 | 
							 	L’axiome de M. Zermelo et son rˆole dans la th´eorie des ensembles et l’analyse, Sierpi'nski,  W. 1918, Bull. Int. Acad. Sci. Cracovie Cl. Math. Nat.  | 
					
| 32 \(\Rightarrow\) 350 | clear | 
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement | 
|---|---|
| 259: | \(Z(TR\&C,W)\): If \((X,R)\) is a transitive and connected relation in which every well ordered subset has an upper bound, then \((X,R)\) has a maximal element.  | 
					
| 260: | \(Z(TR\&C,P)\): If \((X,R)\) is a transitive and connected relation in which every partially ordered subset has an upper bound, then \((X,R)\) has a maximal element.  | 
					
| 40: | \(C(WO,\infty)\): Every well orderable set of non-empty sets has a choice function. Moore, G. [1982], p 325.  | 
					
| 39: | \(C(\aleph_{1},\infty)\): Every set \(A\) of non-empty sets such that \(\vert A\vert = \aleph_{1}\) has a choice function. Moore, G. [1982], p. 202.  | 
					
| 8: | \(C(\aleph_{0},\infty)\):  | 
					
| 27: | \((\forall \alpha)( UT(\aleph_{0},\aleph_{\alpha}, \aleph_{\alpha}))\): The union of denumerably many sets each of power \(\aleph_{\alpha }\) has power \(\aleph_{\alpha}\). Moore, G. [1982], p 36.  | 
					
| 31: | \(UT(\aleph_{0},\aleph_{0},\aleph_{0})\): The countable union theorem: The union of a denumerable set of denumerable sets is denumerable.  | 
					
| 32: | \(C(\aleph_0,\le\aleph_0)\): Every denumerable set of non-empty countable sets has a choice function.  | 
					
| 350: | \(MC(\aleph_0,\aleph_0)\): For every denumerable set \(X\) of non-empty denumerable sets there is a function \(f\) such that for all \(x\in X\), \(f(x)\) is a finite, non-empty subset of \(x\).  | 
					
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