Freeware apps: pdf scissors, briss, k2pdfopt.
http://sourceforge.net/projects/briss/
https://sites.google.com/site/pdfscissors/
http://www.willus.com/k2pdfopt/
k2pdfopt is more powerfull app but in your case it's better to use briss or scissors because they use intuitive visual rectangle boxes for cropping instead of commands.
It takes about 10 seconds to load that 38 page file and ten more seconds for cropping if we know what to do.
Since original cropped file is 15 cm wide we can also try to read it in landscape mode of 6" reader (12 cm width).
To adjust that cropped pdf file for landscape viewing (if our reader is poor or slow at it) we can use k2pdfopt beforehand; just by loading the cropped pdf file into k2pdfopt and choosing fitwidth mode, and after couple of minutes we'll get the third file from attachment.
If letters are very small (as in this case) we can use k2pdfopt's reflow mode instead (default mode, reflow box checked) getting the fourth file from attachment after a couple of minutes.