[{"type":"report","id":"BLC-STUDY-1741","title":"Proof of Payment","author":[{"literal":"Kalle Rosenbaum"}],"issued":{"date-parts":[[2015]]},"publisher":"Kalle Rosenbaum","URL":"https://github.com/bitcoin/bips/blob/master/bip-0120.mediawiki","note":"Rights status: Official external source only. Not a licence to republish the paper."}]