Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, cau treo
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
qua cac » cua cac
cac tac » cac toc, cac bac, cac dac
va hanh » van hanh, va thanh, va danh
hanh ca » hanh cac, hanh cat, hanh cua
ca tren » cu tren, la tren, co tren
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
ma hoi » mai hoi, xa hoi, ma hoa
tac va » tac da, tac xa, tuc va

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 v nang ma hoi. hieu qua cac tac va hanh ca ((cau tren) or (ca tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach v nang ma hoi. hieu qua cac tac va hanh ca ((cau tren) OR (ca tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach v nang ma hoi. hieu qua cac tac va hanh ca ((cau tren) or (ca tren))*.