The Morse code for the 26 letters of the English language and the digits, you can find everywhere, e.g.
here on Wikipedia. All one-, two-, and three-symbol combinations are in use.
In the international alphabet all but four of the four-symbol combinations are used. They are:
Morse | German
++ | Norwegian/
Danish | Spanish | Esperanto | Polish
16.3.2014 | Greek | Russian | Arabic |
·-·- | Ä | Æ | - | - | Ą | - | Я | ع |
---· | Ö | Ø | - | - | Ó | - | Ч | ز |
··-- | Ü | - | - | Ŭ | - | - | Ю | - |
---- | Ch | - | Ch | Ĥ | - | Χ | Ш | ش |
The two or three first German letters are used in many other languages also, e.g. Swedish, Finnish, Turkish, Hungarian etc.
Note that the Ö/Ø Morse code is an O (---) followed by an E (·), usually written as OE. OE also happens to be how the letter is written if the proper symbol isn't available. That also shows the relationship with the French Œ, but that's a digression that has little to do with Morse code. Likewise, the Morse symbols for both the Ä/Æ and the Ü start with the non-accented letter and are AA and UT respectively.