18:0818:08, 23 May 2015diffhist+622
History of submarines
https://books.google.de/books?id=7cDN8q2RHGMC&pg=PA1&lpg=PA1&dq=Yefim+Nikonov+in+1720&source=bl&ots=THN0VQCmn9&sig=Jkt2JpzK-Ei042Geb-qcoVZcfT8&hl=de&sa=X&ei=CL1gVaysDoW7UcT4gaAI&ved=0CDEQ6AEwAg#v=onepage&q=Yefim%20Nikonov%20in%201720&f=false
22:1022:10, 21 May 2015diffhist+26
John Logie Baird
Are you kidding? https://books.google.de/books?id=gZcwhVyiMqsC&printsec=frontcover&dq=Burns+''Television:+An+International+History+of+the+Formative+Years%22&cd=1&hl=de#v=onepage&q=zworykin%20rosing%20selenium&f=false + see article "Mechanical television".
19:1719:17, 20 May 2015diffhist+1
Organ transplantation
https://books.google.de/books?id=XizrBwAAQBAJ&pg=PA3&lpg=PA3&dq=voronoy+Ischemia&source=bl&ots=Dh2U-0VCRV&sig=W3KsWuQTg-Gk8prUtAvgxU6GGb0&hl=de&sa=X&ei=WrFXVb_BKYGfygOqnoGYBw&ved=0CCIQ6AEwAA#v=onepage&q=voronoy%20Ischemia&f=false
18:5618:56, 15 May 2015diffhist+26
John Logie Baird
Rosing was first; https://books.google.de/books?id=gZcwhVyiMqsC&printsec=frontcover&dq=Burns+''Television:+An+International+History+of+the+Formative+Years%22&cd=1&hl=de#v=onepage&q=zworykin%20rosing%20selenium&f=false