diff --git a/src/scgenerator/__init__.py b/src/scgenerator/__init__.py
index eb39f01..7276957 100644
--- a/src/scgenerator/__init__.py
+++ b/src/scgenerator/__init__.py
@@ -6,7 +6,7 @@ from scgenerator.helpers import *
 from scgenerator.logger import get_logger
 from scgenerator.math import abs2, argclosest, normalized, span, tspace, wspace
 from scgenerator.parameter import Parameters
-from scgenerator.spectra import Spectrum, propagation
+from scgenerator.spectra import Spectrum, propagation, propagation_series
 from scgenerator.physics import fiber, materials, plasma, pulse
 from scgenerator.physics.units import PlotRange
 from scgenerator.solver import SimulationResult, integrate, solve43