Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
cua tre » cua te, cuu tre, cua triet
y tang » ky tang, 6 tang, 7 tang
ma hoi » mai hoi, xa hoi, ma hoa
ky cau » ky chau, ke cau
luc va » tuc va, loc va
vi cua » vai cua, di 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)) y tang ma hoi. hieu ky cau ((luc va) or (duc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) y tang ma hoi. hieu ky cau ((luc va) OR (duc va)) hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) y tang ma hoi. hieu ky cau ((luc va) or (duc va)) hanh vi cua tre*.