The article by Fam is devoted to the use of Wigner representation for the two-particle density matrix, which is outside the scope of our article. Moreover, in contrast to that article, we do not use an expansion of the equation for the Wigner distribution in powers of hbar. For both these reasons, we do not include a reference on this article 5.
A second example is the equation 9b for Wigner function: the associated quotation is ref. 17 by one of the authors and M.A. Kasevich in Phys Rev A (2006). A brief search on the web proves that a similar equation was used by Hongyi Fan Phys Rev A 656, 064102 (2002) who quotes two references dating from 1984 and a book published in 1994. I am not sufficiently aware of the use f Wigner function but I am sure that there are better and more useful references to quote in addition to ref 17!