Ngo, HD 1990Bell, TF, Ngo, HD Electrostatic lower hybrid waves excited by electromagnetic whistler mode waves scattering from planar magnetic-field-aligned plasma density irregularities PDF (Online Viewing) 349.pdf 1989Ngo, HD, Helliwell, RA Electrostatic Waves Stimulated by VLF Whistler Mode Waves Scattering from Magnetic-field-aligned Plasma Density Irregularities 1988Bell, TF, Ngo, HD Electrostatic waves stimulated by coherent VLF signals propagating in and near the inner radiation belt