Finance Bills, Supplementary Appropriation Bills, Provisional Appropriation Bills, Government Loan Bills, Civil Servants (Amendment) Bills, Salaries and Pensions Bills, Naturalization Bills, Expropriation Bills, T axation (Direct and Indirect) Bills, as well as Bills introduced for the purpose of discharging existing treaty obligations shall not be submitted to decision by referendum. This provision shall also apply to the Bills referred to in sections 9, 8, 10 and 11, and to such resolutions as are provided for in section 19, if existing in the form of a law, unless it has been prescribed by a special Act that such resolutions shall be submitted to referendum. Amendments to the Constitutional Act shall be governed by the rules laid down in section 88.