Perhaps you should try some spelling variations:
nang rong » nang trong, nang song, nang dong
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
cac tuc » cac toc, cac tu, cac nuoc
cac tac » cac toc, cac bac, cac dac
va hanh » van hanh, va thanh, va danh
cuc » cuoc, chuc
thue » thu, thuc, thuy

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 rong) or (nang ma)) hoi. hieu qua ((cac tuc) OR (cac tac)) va hanh tai cuc thue~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang rong) OR (nang ma)) hoi. hieu qua ((cac tuc) OR (cac tac)) va hanh tai cuc thue.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang rong) or (nang ma)) hoi. hieu qua ((cac tuc) OR (cac tac)) va hanh tai cuc thue".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang rong) or (nang ma)) hoi. hieu qua ((cac tuc) OR (cac tac)) va hanh tai cuc thue*.