To refer to specific individual elements within a general tensor, mathematical notation uses a lowercase letter with multiple subscripts corresponding to the tensor's axes. For example, an individual element within a third-order tensor $\mathsf{X}$ might be referenced as $x_{ijk}$. Alternatively, the tensor's main symbol can be enclosed in brackets with subscripts, such as $[\mathsf{X}]_{1, 2i-1, 3}$.