Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
thanh di » thanh doi, thanh de, thanh do
truc va » thuc va, thuc vat, trung va
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
tuc va » thuc va, tuc xa, duc va
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, doi cua, de cua

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 (thu hoach)) ky nang ma hoi. hieu van cau ((tuc va) OR (truc va)) thanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) ky nang ma hoi. hieu van cau ((tuc va) OR (truc va)) thanh di cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu hoach)) ky nang ma hoi. hieu van cau ((tuc va) OR (truc va)) thanh di cua viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) ky nang ma hoi. hieu van cau ((tuc va) OR (truc va)) thanh di cua viet*.