Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
dat trong » dot trong, vat trong, cay trong
thanh vai » thanh hai, thanh van, thanh tai
hieu van » hieu va, thien van, lieu va
van cam » van nam, van lam, van cau
vai dat » cai dat, va dat, van dat
tu sach » thu sach, su sach, te sach
nang o » nang co, nang ho, nang ro
luc va » tuc va, loc va
o hoi » co hoi, o hoc, o hai

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 (thuoc sach)) ky nang o hoi. hieu van cam ((luc va) OR (duc va)) thanh vai dat trong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky nang o hoi. hieu van cam ((luc va) OR (duc va)) thanh vai dat trong.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) ky nang o hoi. hieu van cam ((luc va) OR (duc va)) thanh vai dat trong".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky nang o hoi. hieu van cam ((luc va) OR (duc va)) thanh vai dat trong*.