Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach thu » sach thue, sach thieu, sach tham
va trinh » van trinh, va tinh, qua trinh
van cac » van hac, van cau, van bac
sach ty » sach y, sach tu, xach tay
nang xa » nang x, lang xa, nang ma
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu van cac nuoc ((va trinh) or (lap trinh)) vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu van cac nuoc ((va trinh) OR (lap trinh)) vi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) nang xa hoi. hieu van cac nuoc ((va trinh) or (lap trinh)) vi cua tu".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu van cac nuoc ((va trinh) or (lap trinh)) vi cua tu*.