Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
hieu cac » hieu luc, hieu va, hieu van
toc sach » hoc sach, doc sach, thuoc sach
nang lai » nang tai, mang lai, nang cai
nam dao » nam dan, nam sao, nam cao
hoc nam » hoc lam
cac hoc » cach hoc, cac hop, bac hoc
tu sach » thu sach, su sach, te sach
lai hoi » dai hoi, lai hoa, lai roi
vi su » va su, ve su, oi su
ki su » ky su

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) or (toc sach)) ky nang lai hoi. hieu hieu cac hoc nam dao ((vi su) or (ki su)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky nang lai hoi. hieu hieu cac hoc nam dao ((vi su) OR (ki su)) tren.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky nang lai hoi. hieu hieu cac hoc nam dao ((vi su) or (ki su)) tren*.