If you are looking for a "useful article" regarding the characters appearing in your topic (specifically the Russian letters and Щ ), Mastering the Sibilants: Ш vs. Щ

In Russian, these two letters are often confused by learners because they both sound like the English "sh," but they are distinct phonemes. : Sound : A "hard" sh sound, similar to "sh" in shoe .

: A "soft" sh sound, like the "sh" in sheep or fresh cheese .