Zheng, ZhaowenMa, YujuanSpringer International PublishingBoundary Value ProblemsZheng, Z., Ma, Y.: Dependence of eigenvalues of 2mth-order spectral problems. Bound. Value Probl. 2017, 126 (2017). https://doi.org/10.1186/s13661-017-0857-y...
A3: We will provide lifelong maintenance service, solve problems for customers free of charge, eliminate all the troubles of customers. For machines beyond the warranty period, we will continue to providing follow-up services. The spare parts just charge the cost price...