Linked from
The 10 pages that link to Longitudinal wave, each with the reason it gives.
P wavesNarrower topic: P waves are the seismic example of this broader wave pattern.
Sound speedRelated: Sound in fluids travels through successive compressions and expansions.
Transverse waveCompared with: It differs from a transverse wave in the orientation of oscillations.
Mechanical waveBroader topic: This is one basic mode of mechanical wave motion.
PlasmonRelated: Bulk plasmons are longitudinal electron-density waves.