How are dictionaries of ideograms sorted? Since Chinese. Japanese and Korean have no alphabetical writing system how do those people sort their dictionaries?
Wikipedia


The second system of dictionary organization is by recurring graphic
components or radicals. (...) As most
Chinese characters are semantic-phonetic ones (形聲字), the radical
method is usually effective, thus it continues to be widely used in
the present day. However, sometimes the radical of a character is not
obvious. To compensate this, a &quot;Chart of Characters that Are Difficult
to Look up&quot; (難檢字表), arranged by the number of strokes of the
characters, is usually provided.

Here is what a chart of radicals in a dictionary looks like


You can otherwise search a character by its pinyin if you know it.

See also: https://www.quora.com/How-do-you-look-up-Chinese-characters-in-a-Chinese-dictionary