Update README.md

README.md

 # melt-blowing
 
 design and prototyping of a FabLab-able polypropylene melt blowing setup for distributed manufacture of filter media
+
+## literature
+dimensional analysis of process and discussion of nozzle types (1988): https://pubs.acs.org/doi/pdf/10.1021/ie00084a021
+Exxon patent showing slot-style melt blowing nozzle: https://patents.google.com/patent/US3849241A/en?oq=3%2c849%2c241
+UTenn study on melt blowing: https://onlinelibrary.wiley.com/doi/epdf/10.1002/pen.760302202
+
+## melt blowing videos
+video of a polypropylene filter melt blowing line in action: https://www.youtube.com/watch?v=cGQ4piMNQ_E
+fast construction of a melt blowing line for covid-19 masks: https://www.youtube.com/watch?v=p9lchhBE7cE
+a smaller line with a built-in rotary mask die cutter: https://www.youtube.com/watch?v=KgWHNQo7j1k
+pilot-scale melt blowing machine making a mess: https://www.youtube.com/watch?v=SOFfpGnMjOc