diff --git a/.gitignore b/.gitignore
index 48b38e5..bffdb66 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,86 +1,23 @@
+# IDE
 .vscode/
+
+# Build
 build/
+
+# Output
 plots/
-results/frames
+results/frames/
+
+# Models
 models/
 neural_models/
-ipddp/
-examples/c_generated_code/acados_sim_solver_car.c
-examples/c_generated_code/acados_sim_solver_car.h
-examples/c_generated_code/acados_sim_solver_quadrotor.c
-examples/c_generated_code/acados_sim_solver_quadrotor.h
-examples/c_generated_code/acados_sim_solver_unicycle.c
-examples/c_generated_code/acados_sim_solver_unicycle.h
-examples/c_generated_code/acados_solver_car.c
-examples/c_generated_code/acados_solver_car.h
-examples/c_generated_code/acados_solver_car.o
-examples/c_generated_code/acados_solver_quadrotor.c
-examples/c_generated_code/acados_solver_quadrotor.h
-examples/c_generated_code/acados_solver_quadrotor.o
-examples/c_generated_code/acados_solver_unicycle.c
-examples/c_generated_code/acados_solver_unicycle.h
-examples/c_generated_code/acados_solver_unicycle.o
-examples/c_generated_code/acados_solver.pxd
-examples/c_generated_code/INTEGRATION_GUIDE.txt
-examples/c_generated_code/libacados_ocp_solver_car.so
-examples/c_generated_code/libacados_ocp_solver_quadrotor.so
-examples/c_generated_code/libacados_ocp_solver_unicycle.so
-examples/c_generated_code/main_car.c
-examples/c_generated_code/main_quadrotor.c
-examples/c_generated_code/main_sim_car.c
-examples/c_generated_code/main_sim_quadrotor.c
-examples/c_generated_code/main_sim_unicycle.c
-examples/c_generated_code/main_unicycle.c
-examples/c_generated_code/Makefile
-examples/c_generated_code/car_model/car_expl_ode_fun.c
-examples/c_generated_code/car_model/car_expl_ode_fun.o
-examples/c_generated_code/car_model/car_expl_ode_hess.c
-examples/c_generated_code/car_model/car_expl_ode_hess.o
-examples/c_generated_code/car_model/car_expl_vde_adj.c
-examples/c_generated_code/car_model/car_expl_vde_adj.o
-examples/c_generated_code/car_model/car_expl_vde_forw.c
-examples/c_generated_code/car_model/car_expl_vde_forw.o
-examples/c_generated_code/car_model/car_model.h
-examples/c_generated_code/quadrotor_model/quadrotor_expl_ode_fun.c
-examples/c_generated_code/quadrotor_model/quadrotor_expl_ode_fun.o
-examples/c_generated_code/quadrotor_model/quadrotor_expl_vde_adj.c
-examples/c_generated_code/quadrotor_model/quadrotor_expl_vde_adj.o
-examples/c_generated_code/quadrotor_model/quadrotor_expl_vde_forw.c
-examples/c_generated_code/quadrotor_model/quadrotor_expl_vde_forw.o
-examples/c_generated_code/quadrotor_model/quadrotor_model.h
-examples/c_generated_code/unicycle_constraints/unicycle_constr_h_fun_jac_uxt_zt.c
-examples/c_generated_code/unicycle_constraints/unicycle_constr_h_fun_jac_uxt_zt.o
-examples/c_generated_code/unicycle_constraints/unicycle_constr_h_fun.c
-examples/c_generated_code/unicycle_constraints/unicycle_constr_h_fun.o
-examples/c_generated_code/unicycle_constraints/unicycle_constraints.h
-examples/c_generated_code/unicycle_model/unicycle_expl_ode_fun.c
-examples/c_generated_code/unicycle_model/unicycle_expl_ode_fun.o
-examples/c_generated_code/unicycle_model/unicycle_expl_vde_adj.c
-examples/c_generated_code/unicycle_model/unicycle_expl_vde_adj.o
-examples/c_generated_code/unicycle_model/unicycle_expl_vde_forw.c
-examples/c_generated_code/unicycle_model/unicycle_expl_vde_forw.o
-examples/c_generated_code/unicycle_model/unicycle_model.h
-examples/acados_ocp_quadrotor.json
-examples/unicycle_acados_ocp.json
-pdf_images/page_0001.png
-pdf_images/page_0002.png
-pdf_images/page_0003.png
-pdf_images/page_0004.png
-pdf_images/page_0005.png
-pdf_images/page_0006.png
-pdf_images/page_0007.png
-pdf_images/page_0008.png
-pdf_images/page_0009.png
-pdf_images/page_0010.png
-pdf_images/page_0011.png
-pdf_images/page_0012.png
-pdf_images/page_0013.png
-pdf_images/page_0014.png
-pdf_images/page_0015.png
-pdf_images/page_0016.png
-pdf_images/page_0017.png
-pdf_images/page_0018.png
-pdf_images/page_0019.png
-pdf_images/page_0020.png
-pdf_images/page_0021.png
+
+# Generated code (acados)
+examples/c_generated_code/
+examples/*_acados_ocp.json
+
+# PDF images
+pdf_images/
+
+# Solver output
 solver_snopt.out
diff --git a/README.md b/README.md
index 3f7d205..bb378d9 100644
--- a/README.md
+++ b/README.md
@@ -183,10 +183,8 @@ make test
 If you want to use this library for ROS2 MPC node, please refer [CDDP MPC Package](https://github.com/astomodynamics/cddp_mpc). You do not need to install this library to use the package. MPC package will automatically install this library as a dependency.
 
 ## References
-* Z. Xie, C. K. Liu and K. Hauser, "Differential dynamic programming with nonlinear constraints," 2017 IEEE International Conference on Robotics and Automation (ICRA), 2017, pp. 695-702, doi: <10.1109/ICRA.2017.7989086>.
 * Y. Tassa, N. Mansard and E. Todorov, "Control-limited differential dynamic programming," 2014 IEEE International Conference on Robotics and Automation (ICRA), 2014, pp. 1168-1175, doi: <10.1109/ICRA.2014.6907001>.
 * Pavlov, A., Shames, I., and Manzie, C., “Interior Point Differential Dynamic Programming,” IEEE Transactions on Control Systems Technology, Vol. 29, No. 6, 2021, pp. 2720–2727.
-* Zhamming Xie's GitHub repository: <https://github.com/ZhaomingXie/CDDP>
 * Yuval Tassa's iLQG/DDP trajectory optimization: <https://www.mathworks.com/matlabcentral/fileexchange/52069-ilqg-ddp-trajectory-optimization>
 * Andrei Pavlov's GitHub repository: <https://github.com/xapavlov/ipddp>