Klaas de Boer & Wilhelm Seggewiss 
Stars and Stellar Evolution [PDF ebook] 

de Boer Klaas :

Klaas de Boer specialized in optical and UV interstellar studies as well as in the UV output of old stars. After postdoctoral periods in Madison (WI, USA), Tübingen (Germany)and Herstmonceux (UK) he became professor at and Director of the Sternwarte of the University of Bonn.Seggewiss Wilhelm :

Wilhelm Seggewiss studied mathematics, physic and astronomy at the universities of München and Münster(Germany) where he got his Ph D in astronomy. After postdoctoral assistantship at Münster he joined the staff of the observatory of the university of Bonn. After 1979 he became professor at Bonn and chairman of the observatory. Main fields of research are evolution of star clusters and the atmospheres of massive stars.