Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cau tren » cu tren, dau tren, ca tren
tang ma » mang may, tang van
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
cam duc » cam xuc, cao duc, pham duc
va danh » va dinh, va hanh, dia danh
dao cau » dat cau, da cau, tao cau
va dan » ca dan, va dao, va dau
ve cam » ve cham, ve cac, va cam

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 cao) or (tang ma)) hoi. hieu ve cam duc ((va danh) OR (va dan)) dao cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky ((nang cao) OR (tang ma)) hoi. hieu ve cam duc ((va danh) OR (va dan)) dao cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky ((nang cao) or (tang ma)) hoi. hieu ve cam duc ((va danh) OR (va dan)) dao cau tren".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky ((nang cao) or (tang ma)) hoi. hieu ve cam duc ((va danh) OR (va dan)) dao cau tren*.