其中有四篇文献年代久远,非常难以查询,费了很多力才得到全文,它们是:
[2]1933.Forced Vibration with combined coulomb and viscous friction.
[3]1964.Forced Vibration of a 2DOF system with combine coulomb and viscous friction.
[4]1979.Response of a base excited system with coulomb and viscous friction.
[12]1972.A linearized analysis for frictionally damped system.
而这些文章正是对库伦模型的干摩擦阻尼最早的解析求解尝试,对理解干摩擦问题有十分重要的意义(遗憾的是学校的图书馆并没有购买这些早期的文献)。