If you haven't looked at how we define democracy yet, I suggest starting there. 

Laws, Norms, and Democratic Backsliding (readings)

V-Dem's reports on Democracy around the World

IDEA's Democratic Assessments Tools 

Less technical academic papers:

Levitsky, Steven, and Lucan Way. "The New Competitive Authoritarianism." Journal of Democracy 31, no. 1 (2020): 51-65. https://dx.doi.org/10.1353/jod.2020.0004. 

Przeworski, Adam. "Who Decides What Is Democratic?" Journal of Democracy 35, no. 3 (2024): 5-16. https://dx.doi.org/10.1353/jod.2024.a930423. 

Case Study: Mexico

Aguilar, Azul A. Aguiar, Rodrigo Castro Cornejo, and Alejandro Monsiváis-Carrillo. "Is Mexico at the Gates of Authoritarianism?" Journal of Democracy 36, no. 1 (2025): 50-64. https://dx.doi.org/10.1353/jod.2025.a947883.   

-VS-

Ríos, Viridiana. "Why Mexico Is Not on the Brink." Journal of Democracy 35, no. 3 (2024): 57-68. https://dx.doi.org/10.1353/jod.2024.a930427. 

Books

Levitsky, Steven, and Daniel Ziblatt. How democracies die. Crown, 2019. (amazon link)

Discussion on the book:

Bunce V. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1103-1104. doi:10.1017/S1537592718002839 

Pérez-Liñán A. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1101-1102. doi:10.1017/S1537592718003043 

Parker CS. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1099-1100. doi:10.1017/S153759271800289X 

Cramer KJ. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1097-1098. doi:10.1017/S1537592718002876 

Connolly WE. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1095-1096. doi:10.1017/S1537592718002888 

Berman S. A Discussion of Steven Levitsky and Daniel Ziblatt’s How Democracies Die. Perspectives on Politics. 2018;16(4):1092-1094. doi:10.1017/S1537592718002852 

Alternatives to Democracy:

What Are the Origins of Communism?

What Is Fascism?

'We the people' The Battle to Define Populism

China's "democracy"