A good question you can ask a “horn expert” if you want to totally stump them is “how many horn concertos did Rosetti write?”
This coming weekend I will be performing one of the Rosetti horn concertos on my faculty recital at Arizona State. A native of Bohemia who adopted an Italianized form of his name, Antonio Rosetti lived from ca. 1750-1792 and was known both as a composer and as a double bass player. And he wrote a lot of music for the horn.
There are two of his solo concertos that are performed with some regularity in the United States, one in D minor (the only minor key Classical horn concerto that I know of) and one that has been published as his Concerto No. 2 in E-flat. These have both been recorded a few times. Digging around on Amazon, tracks 7-9 of this disc are the D-minor concerto, and tracks 4-6 of this disc are the concerto in E-flat that I will be performing. It dates to 1779 and is a very charming work. Click on the links to find sample tracks of both.
I still did not answer the question of how many horn concertos Rosetti composed, and the answer will surprise you. According to Groves he wrote twelve horn concertos, but according to Thomas Hiebert in The Cambridge Companion to Brass Instruments, Rosetti
…wrote at least 21 horn concerti, six of them for two horns. A number of Rosetti’s double concerti are dedicated to Josef Nagel (c. 1750-1802) and Franz Zwierzina (1750-1825), first and second hornists at Wallerstein starting in 1780. Other concerti for low horn are dedicated to Carl Thürrschmidt (1753-97). Thürrschmidt teamed up with the specialist in playing the high horn Johann Palsa (1752-92) to create on of the most celebrated and well traveled of the horn duo teams.
21 concertos! Wow! [UPDATE: See also comment #4, below] I certainly don’t know all of these works of Rosetti but the ones I know I really like. If you are looking for more Classical horn repertoire, I heartily recommend looking into the Rosetti concertos. I wish they were better known in the horn-playing world for as a group they are fine compositions, and I will make it a project of my own to learn more of these, there must be several more gems among those 21 works.