Perhaps you should try some spelling variations:
thien van » thi van
tham thuc » nham thuc, pham thuc, tam thuc
hieu van » hieu va, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
thuc va » thuc vat, thuc dan, thuc day
va dinh » van dinh, va kinh, va tinh
dinh de » dinh ve, dinh du, dinh le
de cua » le cua, te cua, dieu cua
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: tu sach ky tang xa hoi. ((hieu van) OR (thien van)) tham thuc va dinh de cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang xa hoi. ((hieu van) OR (thien van)) tham thuc va dinh de cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. ((hieu van) OR (thien van)) tham thuc va dinh de cua te*.