  We study classical source coding with quantum side-information where the
quantum side-information is observed by a helper and sent to the decoder via a
classical channel. We derive a single-letter characterization of the achievable
rate region for this problem. The direct part of our result is proved via the
measurement compression theory by Winter. Our result reveals that a helper's
scheme that separately conducts a measurement and a compression is suboptimal,
and the measurement compression is fundamentally needed to achieve the optimal
rate region.
