The user made the edits based on the following references:
[1] Ren, S. Y. (2002). Two types of electronic states in one-dimensional crystals of finite length, Annals of Physics(NY). 301: 22-30. (2002).
[2] Ren, S. Y. (2006). Electronic States in Crystals of Finite Size: Quantum confinement of Bloch waves, Springer Tracts in Modern Physics 212, Springer. ISBN-10 0-387-26303-9
[3] Ren, S. Y. (2017). Electronic States in Crystals of Finite Size: Quantum confinement of Bloch waves, (Second edition). Springer Tracts in Modern Physics 270, Springer. ISBN 978-981-10-4718-3