diff --git a/docs/source/pythonapi/data.rst b/docs/source/pythonapi/data.rst
index 144d26306..92cb78548 100644
--- a/docs/source/pythonapi/data.rst
+++ b/docs/source/pythonapi/data.rst
@@ -5,6 +5,9 @@
 Core Classes
 ------------
 
+The following classes are used for incident neutron data, decay data, fission
+and product yields.
+
 .. autosummary::
     :toctree: generated
     :nosignatures:
diff --git a/include/openmc/secondary_thermal.h b/include/openmc/secondary_thermal.h
index 998143d0f..7b876334f 100644
--- a/include/openmc/secondary_thermal.h
+++ b/include/openmc/secondary_thermal.h
@@ -42,6 +42,9 @@ private:
 
 class IncoherentElasticAE : public AngleEnergy {
 public:
+  //! Construct from HDF5 file
+  //
+  //! \param[in] group  HDF5 group
   explicit IncoherentElasticAE(hid_t group);
 
   //! Sample distribution for an angle and energy
@@ -59,11 +62,19 @@ private:
 
 class IncoherentElasticAEDiscrete : public AngleEnergy {
 public:
+  //! Construct from HDF5 file
+  //
+  //! \param[in] group  HDF5 group
+  //! \param[in] energy  Energies at which cosines are tabulated
   explicit IncoherentElasticAEDiscrete(hid_t group, const std::vector<double>& energy);
 
+  //! Sample distribution for an angle and energy
+  //! \param[in] E_in Incoming energy in [eV]
+  //! \param[out] E_out Outgoing energy in [eV]
+  //! \param[out] mu Outgoing cosine with respect to current direction
   void sample(double E_in, double& E_out, double& mu) const override;
 private:
-  const std::vector<double>& energy_; //!< Incoherent inelastic scattering cross section
+  const std::vector<double>& energy_; //!< Energies at which cosines are tabulated
   xt::xtensor<double, 2> mu_out_; //!< Cosines for each incident energy
 };
 
@@ -73,8 +84,16 @@ private:
 
 class IncoherentInelasticAEDiscrete : public AngleEnergy {
 public:
+  //! Construct from HDF5 file
+  //
+  //! \param[in] group  HDF5 group
+  //! \param[in] energy  Incident energies at which distributions are tabulated
   explicit IncoherentInelasticAEDiscrete(hid_t group, const std::vector<double>& energy);
 
+  //! Sample distribution for an angle and energy
+  //! \param[in] E_in Incoming energy in [eV]
+  //! \param[out] E_out Outgoing energy in [eV]
+  //! \param[out] mu Outgoing cosine with respect to current direction
   void sample(double E_in, double& E_out, double& mu) const override;
 private:
   const std::vector<double>& energy_; //!< Incident energies
@@ -89,8 +108,15 @@ private:
 
 class IncoherentInelasticAE : public AngleEnergy {
 public:
+  //! Construct from HDF5 file
+  //
+  //! \param[in] group  HDF5 group
   explicit IncoherentInelasticAE(hid_t group);
 
+  //! Sample distribution for an angle and energy
+  //! \param[in] E_in Incoming energy in [eV]
+  //! \param[out] E_out Outgoing energy in [eV]
+  //! \param[out] mu Outgoing cosine with respect to current direction
   void sample(double E_in, double& E_out, double& mu) const override;
 private:
   //! Secondary energy/angle distribution
diff --git a/src/secondary_thermal.cpp b/src/secondary_thermal.cpp
index 5fdf6201a..696907a17 100644
--- a/src/secondary_thermal.cpp
+++ b/src/secondary_thermal.cpp
@@ -240,13 +240,13 @@ IncoherentInelasticAE::sample(double E_in, double& E_out, double& mu) const
 
   // Determine endpoints on grid i
   auto n = distribution_[i].e_out.size();
-  double E_i_1 = distribution_[i].e_out(0);
-  double E_i_J = distribution_[i].e_out(n - 1);
+  double E_i_1 = distribution_[i].e_out[0];
+  double E_i_J = distribution_[i].e_out[n - 1];
 
   // Determine endpoints on grid i + 1
   n = distribution_[i + 1].e_out.size();
-  double E_i1_1 = distribution_[i + 1].e_out(0);
-  double E_i1_J = distribution_[i + 1].e_out(n - 1);
+  double E_i1_1 = distribution_[i + 1].e_out[0];
+  double E_i1_J = distribution_[i + 1].e_out[n - 1];
 
   double E_1 = E_i_1 + f * (E_i1_1 - E_i_1);
   double E_J = E_i_J + f * (E_i1_J - E_i_J);