1. B. Van der Pol, “On Relaxation Oscillations,” Philos. Mag. 2, 978–992 (1926).
2. A. A. Dorodnitsyn, “Asymptotic Solution of Van der Pol Equation,” Prikl. Mat. Mekh. 11, 313–328 (1947).
3. E. Hairer and G. Wanner, Solving Ordinary Differential Equations II: Stiff and Differential-Algebraic Problems (Springer-Verlag, Berlin, 1996; Mir, Moscow, 1999).
4. V. N. Gridin, V.B. Mikhailov, G. A. Kupriyanov, and K. V. Mikhailov, “Stable Numerical Methods for Superstiff Differential-Algebraic Equations,” Mat. Model. 15(10), 35–50 (2003).
5. C. W. Gear, “Numerical Initial Value Problems in Ordinary Differential Equations,” Prentice Hall, 5, 253 (1971).