An old but important paper in IEEE about two different approaches of inertial navigation system error modeling. it is not available in "IEEE Xplore", but I converted it from microfilm to PDF.

严恭敏_博士学位论文 论文中采用激光陀螺捷联惯导系统为主导航系统，通过与里程计和气压高度计组合，构成车载自主定位定向系统，并借助路标点进行误差补偿。该定位定向系统不依靠 GPS，中途无须停车作零速修正，是一种全自主的导航系统，具有定位定向精度高、机动性好、可靠性高和寿命长等优点。 -In this thesis, laser gyro strapdown inertial navigation system (SINS) is selected as core navigation s