Perhaps you should try some spelling variations:
duoc tren » nuoc tren, thuoc tren, dung tren
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cau tuc » cau truc, cau tu, cau luc
dan tai » van tai, dan thi, han tai
duc tre » duc tien
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau
xa dan » ca dan, xa dai, va dan

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 y nang ma hoi. hieu va cau tuc xa dan tai ((duc tre) or (duoc tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ma hoi. hieu va cau tuc xa dan tai ((duc tre) OR (duoc tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ma hoi. hieu va cau tuc xa dan tai ((duc tre) or (duoc tren))*.