Who are you designing for? What products are already in the market? What information exists about your chosen manufacturing technique?
Example journal articles (note the classic IMRaD structure -- Introduction, Methods, Results, and Discussion)
Wei, Yiran, Krapp, Holger G., Huang, Jiaqi V, & Krapp, Holger G. (2019). A biohybrid fly-robot interface system that performs active collision avoidance. Bioinspiration & Biomimetics, 14(6), 065001. https://iopscience-iop-org.du.idm.oclc.org/article/10.1088/1748-3190/ab3b23
Example review article (a summary of research on a topic):
Daniela Rus, & Michael T. Tolley. (2015). Design, fabrication and control of soft robots. Nature, 521(7553), 467-475. http://dx.doi.org.du.idm.oclc.org/10.1038/nature14543
Example of a seminal work that gets cited over and over again in current research:
Brin, Servey, & Page, Lawrence. (1998). The anatomy of a large-scale hypertextual Web search engine. Computer Networks and ISDN Systems, 30(1), 107-117. https://www-sciencedirect-com.du.idm.oclc.org/science/article/pii/S016975529800110X
Example of an engineering handbook:
Handbook of Metal Injection Molding by 
