References

Stochastic Ray Tracing & Global Illumination
[1] Cook, R. L. 1986. Stochastic sampling in computer graphics. ACM Trans. Graph. 5, 1 (Jan. 1986), 51-72.
[2] Shirley, P., Wang, C., and Zimmerman, K. 1996. Monte Carlo techniques for direct lighting calculations. ACM Trans. Graph. 15, 1 (Jan. 1996), 1-36.
[3] Lawrence, J. 2002. Importance Sampling of the Phong Reflectance Model. Located at: https://www.cs.virginia.edu/~jdl/importance.doc
[4] https://www.dusterwald.com/2016/07/path-tracing-vs-ray-tracing/
[5] https://www.scratchapixel.com/
[6] https://blog.demofox.org/2016/09/21/path-tracing-getting-started-with-diffuse-and-emissive/

Depth Of Field
[1] https://courses.cs.washington.edu/courses/csep557/99au/projects/trace/depthoffield.doc
[2] https://medium.com/@elope139/depth-of-field-in-path-tracing-e61180417027

Bump Mapping 
[1]  James F. Blinn. 1978. Simulation of wrinkled surfaces. In Proceedings of the 5th annual conference on Computer graphics and interactive techniques (SIGGRAPH ’78). ACM, New York, NY, USA, 286-292. DOI=http://dx.doi.org/10.1145/800248.507101
[2] https://graphics.ethz.ch/teaching/former/gdv1_04/GDV1_WS04/exercise/P6_Bump_mapping_hints.pdf
[3] https://squircleart.github.io/shading/normal-map-generation.html