Perhaps you should try some spelling variations:
thuat mach » thuat sach, thuat tach, thuyet mach
van phong » hai phong
mach hoc » cach hoc, dich hoc, anh hoc
cuu cong » cua cong, thu cong, cac cong
cong hoc » dong hoc, cong hoa, cong coc
hoc phan » hoc dan, hoc pho
phan hoa » phan loai, phan phoi, phan hong

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thuat mach hoc tap, nghien cuu cong hoc phan hoa hoc ma hoa ((van phong) or (van dong)) van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat mach hoc tap, nghien cuu cong hoc phan hoa hoc ma hoa ((van phong) OR (van dong)) van.
• Adding a wildcard symbol may retrieve word variants: thuat mach hoc tap, nghien cuu cong hoc phan hoa hoc ma hoa ((van phong) or (van dong)) van*.