“ It is obvious that petitioner cannot sell its gas burners, whatever may be their virtues, if, because of the alleged conspiracy, the purchasers cannot buy gas for use in those burners. The conspiratorial refusal 'to provide gas for use in the plaintiff's Radiant Burner (s) (because they) are not approved by AGA' therefore falls within one of the 'classes of restraints which from their 'nature or character' (are) unduly restrictive, and hence forbidden by both the common law and the statute. ”

“ It stated that 'No boycott, conspiracy to boycott or other form of per se violation is established by the facts alleged' (id., at page 199) , and that ' (i) n the absence of a per se violation the Sherman Act protects the individual injured competitor and affords him relief, but only under circumstances where there is such general injury to the competitive process that the public at large suffers economic harm.' Id., at page 200. ”