Here are some useful resources,
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4110170/
https://www.ncbi.nlm.nih.gov/pmc/?term=materials+for+laryngoscope
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4487700/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3788226/
http://www.canadaessaywriting.com/
Here are some URLs
https://www.ncbi.nlm.nih.gov/pmc
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683880/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4506834/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3464269/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276373/
http://canadaessaywriting.com/