Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
doi cua » dai cua, hoi cua, dong cua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van cau » van dau, van hau, van chat
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
di cua » dai cua, de cua, do cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky ((nang ma) or (sang ma)) hoi. hieu van cau thuc va hanh ((di cua) or (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky ((nang ma) OR (sang ma)) hoi. hieu van cau thuc va hanh ((di cua) OR (doi cua)) tre.
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky ((nang ma) or (sang ma)) hoi. hieu van cau thuc va hanh ((di cua) or (doi cua)) tre*.