61 STAT.] 80TH CONG. , 1ST SESS.-CH. 120-JUNE 23, 1947 practice) to require as a condition of employment membership therein on or after the thirtieth day following the beginning of such employment or the effective date of such agreement, which- ever is the later, (i) if such labor organization is the representative of the employees as provided in section 9 (a), in the appropriate collective-bargaining unit covered by such agreement when made; and (ii) if, following the most recent election held as provided in section 9 (e) the Board shall have certified that at least a majority of the employees eligible to vote in such election have voted to authorize such labor organization to make such an agreement: Provided further, That no employer shall justify any discrimina- tion against an employee for nonmembership in a labor organiza- tion (A) if he has reasonable grounds for believing that such membership was not available to the employee on the same terms and conditions generally applicable to other members, or (B) if he has reasonable grounds for believing that membership was denied or terminated for reasons other than the failure of the employee to tender the periodic dues and the initiation fees uniformly required as a condition of acquiring or retaining membership; " (4) to discharge or otherwise discriminate against an employee because he has filed charges or given testimony under this Act; "(5) to refuse to bargain collectively with the representatives of his employees, subject to the provisions of section 9 (a). "(b) It shall be an unfair labor practice for a labor organization or its agents- "(1) to restrain or coerce (A) employees in the exercise of the rights guaranteed in section 7: Provided, That this paragraph shall not impair the right of a labor organization to prescribe its own rules with respect to the acquisition or retention of member- ship therein; or (B) an employer in the selection of his repre- sentatives for the purposes of collective bargaining or the adjust- ment of grievances; "(2) to cause or attempt to cause an employer to discriminate against an employee in violation of subsection (a) (3) or to discriminate against an employee with respect to whom member- ship in such organization has been denied or terminated on some ground other than his failure to tender the periodic dues and the initiation fees uniformly required as a condition of acquiring or retaining membership; "(3) to refuse to bargain collectively with an employer, pro- vided it is the representative of his employees subject to the provisions of section 9 (a); "(4) to engage in, or to induce or encourage the employees of any employer to engage in, a strike or a concerted refusal in the course of their employment to use, manufacture, process, transport, or otherwise handle or work on any goods, articles, materials, or commodities or to perform any services, where an object thereof is: (A) forcing or requiring any employer or self-employed person to join any labor or employer organization or any employer or other person to cease using, selling, handling, transporting, or otherwise dealing in the products of any other producer, processor, or manufacturer, or to cease doing business with any other person; (B) forcing or requiring any other employer to recognize or bar- gain with a labor organization as the representative of his employees unless such labor organization has been certified as the representative of such employees under the provisions of section 9; (C) forcing or requiring any employer to recognize or bargain with a particular labor organization as the representative of his 141 Labor organization or agents. Engaging in oertain strikes, etc.