Vjacheslav Schelokov, the Russian trumpet pedagogue and composer, studied trumpet with Mikhail Tabakov and composition with Alexander Alexandrov and Anatoly Alexandrov at the Moscow Conservatory. After graduating and becoming the chair of the wind department there, he composed this incredible set of trumpet studies.
Following in the footsteps of great Russian composers like Berdiev and Ginetsinsky, he challenges modern players with intervals, articulations, and stylistic elements that are guaranteed to keep you busy, and more importantly, thoroughly satisfied.
I have included a study for free that I particularly like. If you dig it, click above and grab the full set. I think you will be glad you did.