I am attaching a file with some functions and their sources for a Keynesian investment function. Modern growth theories incorporate neoclassical and modern function, and can be gotten from a standard macro text.
Dear Rashmi Ahuja, Prof Ramrattan's answers are in order. In addition I would suggest that you google-search for litreature in your topic and floods of relevant literature would emerge for you to read and select ones of interest. Good luck!
Thanks Sebastain for your reply but problem is i am not finding something concrete on literature on investment dd function on google and even google scholar. So thought of asking it here to the other researchers.