- Tsvetana Stoyanova, “Stokes Matrices of a Reducible Double Confluent Heun Equation via Monodromy Matrices of a Reducible General Huen Equation with Symmetric Finite Singularities”, J Dyn Control Syst, 28, № 1, 2022, 207

- Michał Zakrzewski, Henryk Żołądek, “Linear differential equations and multiple zeta-values. III. Zeta(3)”, Journal of Mathematical Physics, 53, № 1, 2012, 013507

- A. Ya. Kazakov, “Coalescence of Two Regular Singularities into One Regular Singularity for the Linear Ordinary Differential Equation”, Journal of Dynamical and Control Systems, 7, № 1, 2001, 127

- A. A. Glutsyuk, “Resonant Confluence of Singular Points and Stokes Phenomena”, Journal of Dynamical and Control Systems, 10, № 2, 2004, 253
