محاضرة "انتشار أمواج الراديو" للأستاذ محمد بكر ريحان

Round-13 hunt: picked; source: round-12 depth-check holdout re-reviewed at the normal bar; channel screens (sellers/exam/re-upload/devotional/vendor/events), provenance check, vendor/seller/devotional recheck and quality tier C passed; strict per-title check + final strict pass; oEmbed verified.