Professors, Teachers and Researchers
(1) Subject to the provisions of Article 19 and notwithstanding the provisions of Articles 14 and 15, remuneration which a professor, teacher or researcher who is a resident of a Contracting State and who is present in the other Contracting State solely for the purpose of teaching or engaging in research, or both, at a university, college, school or other accredited educational or research institution, derives in respect of such activity, shall be taxable only in the first-mentioned State if the activity of such individual in the other State is supported mainly by public funds of the first-mentioned State or political subdivisions or local authorities thereof.
(2) This Article shall apply for a period not exceeding two years from the date of the first arrival of the professor, teacher or researcher in a Contracting State for the purpose of teaching or engaging in research, or both. An individual shall be entitled to the benefits of this Article only once.
(3) This Article shall not apply to income from research if such research is undertaken not in the public interest but primarily for the private benefit of a specific person or persons.