Pitchfork and Fold/Fold bursting of time delay duffing systems with parametric excitation and external excitationYani Chen, Danjin Zhang and Bingwen LinEur. Phys. J. Spec. Top., 231 11-12 (2022) 2211-2221DOI: https://doi.org/10.1140/epjs/s11734-021-00394-5