Bart Los, Marcel Timmer and Gaaitzen de Vries have published in the  American Economic Review . Their article is title "Tracing Value-Added and Double Counting in Gross Exports: Comment" and they propose a method that provides a clear definition of domestic value added in exports and has a natural extension into decompositions of bilateral export flows, in a more parsimonious way than an earlier approach by Koopman, Wang and Wei (2014).