Perhaps you should try some spelling variations:
nang cai » nang cao, nang cap, nang can
nang tai » hang tai, tang tai, sang tai
cham duc » pham duc, cham soc, pham duy
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va
va hanh » van hanh, va thanh, va danh
cuc tre » duc tre, cua tre, cuu tre

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang cai) OR (nang tai)) hoi. ((hieu va) or (hieu qua)) cham duc va hanh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang cai) OR (nang tai)) hoi. ((hieu va) OR (hieu qua)) cham duc va hanh tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang cai) OR (nang tai)) hoi. ((hieu va) or (hieu qua)) cham duc va hanh tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang cai) OR (nang tai)) hoi. ((hieu va) or (hieu qua)) cham duc va hanh tai cuc tre*.