Recently Bezerra, Garcia and Stichtenoth constructed an explicit tower of function fields over a finite field , whose limit attains the Zink bound . Their proof is rather long and very technical. In this paper we replace the complex calculations in their work by structural arguments, thus giving a much simpler and shorter proof for the limit of the Bezerra, Garcia and Stichtenoth tower.
Academic Press
Journal of Number Theory

Bassa, A., & Stichtenoth, H. (2007). A simplifed proof for the limit of a tower over a cubic finite field. Journal of Number Theory, 123(1), 154–169.