Cello Technique Writers

What a neat "Tarantella" for cello and piano! Tarantella, by Adolphe Fischer
I have been spending a little bit of time trying to (unsuccessfully) track down cello technique writers lately: Heinz Hahnel, who wrote "30 Melodische Etuden fur Violoncello" back in 1985, and Gabriel Negoescu, who wrote "Tecnica Elemental del Violonchelo"; five incredible books on... first position! He covers nearly everything, from open strings, to scales, from half position to extended position, from bowings to rhythms. Volume 1C is my favorite; an absolutely brilliant exposition on extended first position. I really want to know if he has written anything else; Google isn't showing anything. But if these five volumes are all he has written, he has still made an invaluable addition to the library of available cello technique.