(1) Income derived by a resident of a Contracting State in respect of professional services or other independent activities of a similar character shall be subjected to tax only in that State unless he has a fixed base regularly available to him in the other Contracting State for the purpose of performing his activities. If he has such a fixed base, such part of that income as is attributable to that base may be taxed in that other Contracting State.
(2) The term `professional services` includes especially independent scientific literary, artistic, educational or teaching activities as well as the independent activities of physicians, lawyers, engineers, architects, dentists and accountants.
