such speedy development.” Id. at 409, 125 P.2d at 967. The parties to this action agree that an implied covenant to market exists at some point, but both have failed to find support for either the position that the covenant operates, or the position that it does not operate, in the primary term of the lease. Sandlin contends that he produced and marketed oil in the primary term, , 70 S.W.2d 3 (1934) (same); Severson v. Barstow, 103 Mont. 526, 63 P.2d 1022 (1936) (same); Young v. Dixie Oil Co., 647 S.W.2d 235 (Tenn.App.1982) (implied duty imposed upon lessee to diligently explore, operate, and market the product is a continuing one, but the payment of shut-in royalties under the lease extends the lease into the secondary term); Reid v. Gulf Oil Corp., 323 S.W.2d 107 (Tex.Civ.App.1959) (<HOLDING>), aff'd, 161 Tex. 51, 337 S.W.2d 267 (1960);
holding that a contract for an exclusive agency to market a product contains an implied promise to use all reasonable efforts to market the product recognizing implied covenant to market gas recognizing implied duty to produce and market recognizing an implied fourth amendment action for damages recognizing implied obligation to use reasonable diligence