Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
dinh tri » chinh tri
sach ky » sac ky, sach y, sach ty
tri cau » tri cac, tri dau, trinh cau
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
sang ma » tang ma, nang ma, sang tao
xuc va » duc va, tuc va, luc va
va cam » va cham, va cac, va cao

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 ky ((nang x) or (sang ma)) hoi. hieu va cam ((xuc va) or (thuc va)) dinh tri cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang x) OR (sang ma)) hoi. hieu va cam ((xuc va) OR (thuc va)) dinh tri cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang x) or (sang ma)) hoi. hieu va cam ((xuc va) or (thuc va)) dinh tri cau tren*.