Correction to the article: There is no Ů in Czech (except for CAPS LOCKED words) - The longer "u" is written as "Ú/ú" as the first letter in a word, and "ů" in other positions (strange for sure, but because of historical reasons)
(Also, see how I sneaked in a "Ů" in the second sentence :)).
[1] https://en.wikipedia.org/wiki/Alternation_%28linguistics%29