From what I can tell, all three of those are using the same translation; the different titles are down to different publishers.

According to ISFDb both [*You Shall Know Them*][1] and [*Borderline*][2] were translated by [Rita Barisse][3].  [Vercors][4] was her husband and she translated [many of his works][5].  Given that, we should likely consider this a canonical translation.

This appears to be a case where the same book was published with different titles in the U.S. market (*You Shall Know Them*: [Little, Brown and Company][6]) and the U.K. market (*Borderline*: [Macmillan and Co.][7]).

As for [*The Murder of the Missing Link*][8], the [linked review][9] has this to say:

> The ridiculous title conceals Vercors' "You Shall Know Them," and has the one beneficial result of giving it a mystery classification, and hence a lower price than SF.

This edition has "(Original title: YOU SHALL KNOW THEM)" on the cover:

[![Cover of "The Murder of the Missing Link", woman in yellow dress and drawing of a syringe in the background][10]][11]

(Note that the same reviewer had [previously reviewed][12] *You Shall Know Them* when it was released, so he would presumably have noted any differences as that would have been germane to his review.)


  [1]: https://www.isfdb.org/cgi-bin/title.cgi?20515
  [2]: https://www.isfdb.org/cgi-bin/title.cgi?909879
  [3]: https://fr.wikipedia.org/wiki/Rita_Barisse
  [4]: https://fr.wikipedia.org/wiki/Vercors_(%C3%A9crivain)
  [5]: https://www.amazon.com/Vercors-Translated-Rita-Barisse/s?k=Vercors%20Translated%20By%20Rita%20Barisse
  [6]: https://www.isfdb.org/cgi-bin/publisher.cgi?248
  [7]: https://www.isfdb.org/cgi-bin/publisher.cgi?30790
  [8]: https://www.isfdb.org/cgi-bin/title.cgi?187133
  [9]: https://archive.org/details/Astounding_v63n01_1959-03_EXciter-LennyS/page/n147
  [10]: https://i.sstatic.net/4dyDNl.jpg
  [11]: https://i.sstatic.net/4dyDN.jpg
  [12]: https://archive.org/details/Astounding_v53n03_1954-05_cape1736/page/n148