The two books I know about electromagnetism do not provide the derivation of the general expression of the magnetic field near a cirular loop. Perhaps because they are introductory books. The names of the books are Purcell, Electricity and Magnetism and Griffiths, Introduction to Electrodynamics.
I have tried internet too, but without finding anything.
I am looking for this general expression, because it is a prerequisite expression in the proof, proving that the magnetic field outside an ideal solenoid is zero.
Do you have some advanced book reference, where I could find the derivation of the circular wire magnetic field?
PS: I should specify that I have an intermediate level (not advanced at all).