I am currently doing the analysis using firm-level data of three countries combining together. Also, it is a cross-sectional analysis. Therefore, in the regression, I control for industry dummies to account for differential effects in industry level.
I think I don't need to control for country dummies due to some reasons: (1) The countries that I use in my analysis share similar characteristics including development level, political, and socio-economic conditions. (2) There are only three countries in my analysis.
In this case, I expect that the results will not be affected even though I don't control for country specifics.
However, I am not sure if my idea is appropriate since I cannot find any reference to support it yet. Therefore, I would like to ask everybody here if you have any idea whether or not country dummies is necessary in my case.