This question already has an answer here:
To be more specific: Let the random variable X be distributed according to probability density function f(x). Then the pdf of Y=1/X is given by g(y)=1/y^2 f(1/y), see wikipedia.
I wonder if there is any citable reference for that. Or is it common knowledge? I'm coming from a different field of mathematics and lack some background in statistics. I looked through some text books, but didn't find any mention of it yet.
Thanks a lot!