Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, nang ma, sang tao
hanh de » hanh ve, hanh kem
cua tre » cuu tre, dua tren, cua thep
ky sang » ky nang, ky dang, ky tang
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky sang ma hoi. hieu va cau truc van hanh de ((((cua tre) or (cua triet))) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky sang ma hoi. hieu va cau truc van hanh de ((((cua tre) OR (cua triet))) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky sang ma hoi. hieu va cau truc van hanh de ((((cua tre) or (cua triet))) or (cua te))*.