J. A. Lopez and C. Walter, “Is Implied Correlation Worth Calculating? Evidence from Foreign Exchange Options and Historical Data,” Journal of Derivatives, Vol. 7, No. 3, 2000, pp. 65-82.
http://dx.doi.org/10.3905/jod.2000.319125

has been cited by the following article:

• TITLE: Estimating Realistic Implied Correlation Matrix from Option Prices

  AUTHORS: Kawee Numpacharoen, Nattachai Numpacharoen

  KEYWORDS: Realistic Implied Correlation Matrix; Positive-Semi Definite; Valid Correlation Matrix; Implied Correlation Index; Equicorrelation Matrix

  JOURNAL NAME: Journal of Mathematical Finance, Vol.3 No.4, October 17, 2013

  ABSTRACT: The purpose of this research is to derive a new algorithm for obtaining a realistic implied correlation matrix. One contemporary method has a limited scope from its simplified assumption of equicorrelation matrix. However, the result of this limitation is not realistic and cannot be applied to most applications. Another existing method may produce the realistic correlation matrix that is not positive-semi definite. To handle this problem, we expand the existing algorithm to obtain the realistic implied correlation matrix by using the relationship between two implied volatilities of the portfolio of underlying assets.