Perhaps you should try some spelling variations:
thien van » thi van
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
nam hoc » nam moc, nam hoi, am hoc
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
cu tren » tu tren, dua tren
di cu » di cau, di cua, di du

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang xa) or (lang xa)) hoi. thien van nam hoc va hang di cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (lang xa)) hoi. thien van nam hoc va hang di cu tren.
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang xa) or (lang xa)) hoi. thien van nam hoc va hang di cu tren*.