Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va tinh » may tinh
va danh » va dinh, va dan, va hanh
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
lang ha » long ha
vi cua » vai cua, di cua
ve cac » va cac, vien cac

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 y ((nang ma) or (lang ha)) hoi. hieu ve cac du ((va danh) or (va tinh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang ma) OR (lang ha)) hoi. hieu ve cac du ((va danh) OR (va tinh)) vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang ma) or (lang ha)) hoi. hieu ve cac du ((va danh) or (va tinh)) vi cua tre*.