Help, need info on Schubert impromptu

[SunyDiva]

Hi everyone:
Does anybody know where i can find the detail biography of Franz Schubert and his impromptu op.142?

[thierry13]

Schubert's bio :

http://w3.rz-berlin.mpg.de/cmp/schubert.html

Took 20 seconds to find, first result on google search... Did you knew search existed 

And for the impromptu there is not only one in op.142, so wich one??

[SunyDiva]

if i could find the exact biography on why did he write all the impromptu, y did i come here and ask people...
ps: those interenet sites never give enough info for detailed analysis of the composer related to the piece.