I'm having a bit of a difficulty determining some of the resistors in parallel and in series with each other... In the image in attachment when we use the Superposition theorem and remove the 1ma current source and substitute it by an open circuit,how are R1 and R3 related to each other,series or parallel? Also,because of the open circuit shouldn't be R1 removed,since the current passing through it equals 0? And what about R2 and R3 when we remove the 3ma current source?In my perspective I think that it would be equal to removing them,since there won't be any current flowing throw them since the path where the current flowed through the + side of the voltage source to the - side has been cut off. Any help on this is very welcomed!