Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
va thanh » gia thanh, ban thanh, va tinh
nang cai » nang tai, nang cap, nang can
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach kem
ve cam » ve cham, ve cac, va cam
dai va » mai va
thiet » thieu

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) or (sach ty)) ((nang cai) or (nang cao)) hoi. hieu ve cam duc va thanh dai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) ((nang cai) OR (nang cao)) hoi. hieu ve cam duc va thanh dai va thiet.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) ((nang cai) or (nang cao)) hoi. hieu ve cam duc va thanh dai va thiet*.