Max Planck Institute for Psycholinguistics was created in 1980.
It's the same as English.
The word max contains a short A vowel sound (ah as in apple).
The antecedent for the relative pronoun 'who' is Max.The pronoun 'who' introduces the relative clause 'who is from Switzerland'.The relative clause 'who is from Switzerland' provides information that 'relates' to the antecedent noun 'Max'.
You would write the latter, "Max's." It is generally accepted that to make a proper noun that ends in an "x' possessive, you need to add an "'s." The only exceptions are some French and other similar words with a silent "x" like "Bordeaux'" and "Vorreax'."
Max Baldry is fluent in English and is also proficient in French and German.
Max Planck Institute for Physics was created in 1917.
Max Planck Institute for Chemistry was created in 1911.
Max Planck Institute for Mathematics was created in 1980.
Max Planck Institute for Astronomy was created in 1967.
Max Planck Institute for Biology was created in 1912.
Max Planck Institute of Psychiatry was created in 1917.
Max Planck Institute for Astrophysics was created in 1958.
Max Planck Institute for Biogeochemistry was created in 1997.
Max Planck Institute of Quantum Optics was created in 1981.
Max Planck Institute for Biology of Ageing was created in 2008.
Max Planck Institute for Evolutionary Biology was created in 1891.
Max Planck Institute for Brain Research was created in 1914.