Principles of Electrodynamics and Relativity / Prinzipien der Elektrodynamik und Relativitatstheorie - S. Flügge - Bog

will be "asymptotically integrable", that is to say, if we displace a vector parallel to itself along a closed curve whose total length is proportional to r, then, as we remove the curve to infinity, the change of the vector that results from the circuit about the curve will tend to zero.