Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
hieu su » hieu sau, tieu su, hieu so
danh di » danh du, xanh di, danh dien
va danh » va dinh, va dan, va hanh
cham so » cham soc, cham o, ham so
cuu tre » cua tre, cau tren, cau treo
hieu vu » hieu va, hieu ve, dieu vu
nang xa » nang x, lang xa, nang ma
va nang » van nang, da nang, cam nang
di cuu » di cau, di cua, dinh cuu
so va » so van, so vat, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) OR (hoc sinh)) va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) va nang xa hoi. ((hieu vu) OR (hieu su)) cham so va danh di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) OR (hoc sinh)) va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di cuu tre*.