ARTICLE 21
Professors and Teachers
(1) A professor or teacher who visits one of the Contracting States for a period not exceeding two years reckoned from the date he first visits that Contracting State for the sole purpose of teaching or carrying out advanced study (including research) at a university, college or other recognised research institute or other establishment for higher education in that Contracting State and who was immediately before that visit a resident of the other Contracting State shall be exempt from tax in the first-mentioned Contracting State on any remuneration for such teaching or study.
(2) The preceding provisions of this Article shall not apply to remuneration which a professor or teacher receives for conducting research if the research is undertaken primarily for the private benefit of a specific person or persons.