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R&D expenditure and sales : a nonparametric analysis
Nahm, Joon-woo, (1996)
Nonparametric poolability test : test for difference between means in regressions
Nahm, Joon-woo, (1998)
Nonparametric quantile regression analysis of R&D-sales relationship for Korean firms
Nahm, Joon-woo, (2001)