Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
cau phuc » chau phu, huu phuc, van phuc
hanh de » hanh ve, hanh kem
sach ky » sac ky, sach y, sach ty
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
cua tre » cua te, cuu tre, cua triet
de cua » le cua, te cua, dieu 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 (tang ma)) hoi. hieu van ((cau phuc) OR (cau truc)) van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky ((nang ma) OR (tang ma)) hoi. hieu van ((cau phuc) OR (cau truc)) van hanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky ((nang ma) or (tang ma)) hoi. hieu van ((cau phuc) OR (cau truc)) van hanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky ((nang ma) or (tang ma)) hoi. hieu van ((cau phuc) OR (cau truc)) van hanh de cua tre*.