https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.10539 (Publisher version)
Avdievich, N., Krymov, V., & Hetherington, H. (2003). Modified perturbation method for transverse electromagnetic (TEM) coil tuning and evaluation. Magnetic Resonance in Medicine, 50(1), 13-18. doi:10.1002/mrm.10539.