If you publish results obtained with EasySpin, please cite

Stefan Stoll, Arthur Schweiger
EasySpin, a comprehensive software package for spectral simulation and analysis in EPR
J. Magn. Reson. 178(1), 42-55 (2006)

EasySpin's pulse simulation capabilities are described in detail in

Stefan Stoll, R. David Britt
General and efficient simulation of pulse EPR spectra
Phys. Chem. Chem. Phys. 11, 6614-6625 (2009)

This is a short overview of the choices and decisions a user faces when simulating solid-state EPR spectra:

Stefan Stoll
CW-EPR Spectral Simulations: Solid State
Methods in Enzymology 563, 121-142 (2015)

Here is a review that contains over 500 references on theoretical aspects of EPR spectral simulation:

Stefan Stoll
Computational modeling and least-squares fitting of EPR spectra
in: Sushil K. Misra (ed.), Handbook of Multifrequency Electron Paramagnetic Resonance: Data and Techniques, Wiley-VCH, 2014, pp. 69-138

The following article describes the frequency-domain simulation capabilities of EasySpin:

Joscha Nehrkorn, Joshua Telser, Karsten Holldack, Stefan Stoll, Alexander Schnegg
Simulating Frequency-Domain Electron Paramagnetic Resonance: Bridging the Gap between Experiment and Magnetic Parameters for High-Spin Transition-Metal Ion Complexes
J. Phys. Chem. B 119, 13816-13824 (2015)

The equations for the calculation of the cw EPR transition rates are described in

Joscha Nehrkorn, Alexander Schnegg, Karsten Holldack, Stefan Stoll
General Magnetic Transition Dipole Moments for Electron Paramagnetic Resonance
Phys. Rev. Lett. 114, 010801 (2015)

The following article focuses on nitroxide radicals, but is a bit outdated:

Stefan Stoll, Arthur Schweiger
EasySpin: Simulating cw ESR spectra
Biol. Magn. Reson. 27, 299-321 (2007)

This PhD thesis outlines many of the EasySpin simulation methods for cw EPR spectra:

Stefan Stoll
Spectral Simulations in Solid-State Electron Paramagnetic Resonance
ETH Zürich, PhD thesis no. 15059 (2003)

Powerpoint slides

Here is a long PowerPoint slidedeck that serves as the basis for EasySpin presentations at conferences, workshops and summer schools.