At the start of 1919 the Crimea was largely White, sheltered from the Bolsheviks by the Ukraine. The rapid fall of the UNR however led to a conquest by Red forces under Pavel Dybenko. After a short while, however, Denikin launched his offensive into Southern Russia, and the Bolshevks were thrown out.
This offers some interesting options to game, with very small forces involved.
Red Crimea 1919 by M. V. Vladimirski
This is a very full account, from the Soviet side. This is only the first third, which relates to the military aspects.
Notes of a White Officer by S. N. Shidlovskiy
The first half of the memoirs of a White artillery officer that served in the Crimea at the time. There are some errors in his account, especially place names, but it gives a view of the man on the ground.
The Simferopol Officer Regiment by V. V. Almendinger
The history of one of the main units of the White army in the Crimea in 1919. This section deals with the period on the peninsula only. The second part, which is the fighting in the Ukraine against Makhno and the UNR is here.
The units of the White army in the accounts above can be a bit hard to follow because of their rapidly changing names and structures. These pages give the names and structures of the units of the Crimean-Azov Army in its various variants.