Figure 1. Hexagonal lattice a) sheet b) single-walled nanotube

From

Vibration of Single-Walled Carbon Nanotubes by Using Nonlocal Theory

Jozef Bocko, Pavol Lengvarský

American Journal of Mechanical Engineering. 2014, 2(7), 195-198 doi:10.12691/ajme-2-7-5