How Do You Write Country-Related Words?

We always write country-related words with a capital letter. 

Languages are capitalised:

I learnt French and German at school and later Latin and Dutch.
One of my sons speaks Mandarin.

The people are capitalised:

They spoke about the Bosniaks, the Serbs and the Croats.

And the adjectives are capitalised:

I bought a new German book yesterday.
We love Indian curries.
She is Swiss.

I thought you might like to be reminded!