Request from a Tankie: numerical historical analysis on anarchist repression by communists during the Spanish Civil War

To start things well: I'm not trying to start an argument, and I'm not trying to ask for this in bad faith. I'm a Spanish Marxist-Leninist who despises the fact that the Second Republic did nothing about fascists until it was too late.

When I discuss the topic of the Soviets being the only ones to materially help the antifascists in Spain (selling modern tanks and aviation, rifles, munitions and teaching them how to use them), very often I encounter anarchists bringing up the repression of anarchists by communists, particularly related to the Barcelona events. However, when I've asked for literature with a quantitative analysis of this, I've never been given any numerical estimate of the extent of the repression. The Proles Pod episode (Timestamp: 1:18:00) on the Stalin Eras that touches the Spanish Civil War quotes the estimate that less than 20 anarchists were confirmed to have been killed by Soviet agents during the entirety of the conflict, but they only mention the study and they don't name it as far as I've found.

When this happens, I'm often told to read a book. I've found and read many estimates of Soviet repression in the USSR in different works, but never encountered anything about communist repression of anarchists with numerical data attached regarding Spain. So this is my request: I don't want personal anecdotes of an anarchist in prison, I want actual, modern, historically sound numerical estimates of this repression. There are such things for, for example, the Makhnovschina, so there must be something similar for republican Spain. Ofc, I can accept sources both in English and in Spanish!

Thanks a lot <3