Simple megastable oscillators with different types of attractors; tori, chaotic and hyperchaotic onesBiqun Chen, Karthikeyan Rajagopal, Ibrahim Ismael Hamarash, Anitha Karthikeyan and Iqtadar HussainEur. Phys. J. Special Topics, 229 6-7 (2020) 1155-1161DOI: https://doi.org/10.1140/epjst/e2020-900240-1