HES: QUERY--Hayek, Reig, Marx questions

[Michael White]

Can anyone help with the following queries?

In the Appendix B to Hayek's Fatal Conceit, there is a reference to Marx having abandoned work on capital after learning about the analyses of Jevons and Menger. The reference given for the claim is an introduction, written by Joachim Reig, to a Spanish translation of a text by Bohm-Bawerk. No reference was given for that text in the Conceit's bibliography. 
Is there an English translation of Reig's intro? 
Is there any discussion - in English - of this claim about Marx?

Mike White