Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
dai huu » dao huu, dai hau, dai thua
dai cuu » dai cua
va hanh » van hanh, va thanh, va danh
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
lang ha » long ha
lang xa » dang xay, lang van
va cam » va cham, va cac, va cao

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 ((lang xa) or (lang ha)) hoi. hieu va cam duc va hanh ((dai cuu) OR (dai huu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang xa) OR (lang ha)) hoi. hieu va cam duc va hanh ((dai cuu) OR (dai huu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((lang xa) or (lang ha)) hoi. hieu va cam duc va hanh ((dai cuu) OR (dai huu)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang xa) or (lang ha)) hoi. hieu va cam duc va hanh ((dai cuu) OR (dai huu)) tre*.