Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
hoc sach » hoc sinh, hoc cac, hoc anh
thi van » thi lan, thi hanh, thi nang
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc dan, thuc day
va dinh » van dinh, va kinh, va tinh
dinh du » dinh duc, dinh cu, dinh tu
cua tre » cuu tre, cua triet, dua tren
ma hoi » mai hoi, xa hoi, ma hoa
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: hoc sach ky nang ma hoi. ((thien van) or (thi van)) tham thuc va dinh du ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang ma hoi. ((thien van) OR (thi van)) tham thuc va dinh du ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang ma hoi. ((thien van) or (thi van)) tham thuc va dinh du ((cua tre) or (cua te))*.