Perhaps you should try some spelling variations:
su sach » so sach, vu sach
dinh vi » dinh ve, dinh viet, dinh tri
va dinh » van dinh, va kinh, va tinh
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
nang ma » tang ma, sang ma, nang cao
ve cac » va cac, vien cac
vi cuu » vi luu, vinh cuu
ve cam » ve cham, va cam, ve cai

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 x) or (nang ma)) hoi. hieu ((ve cam) OR (ve cac)) duc va dinh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang x) OR (nang ma)) hoi. hieu ((ve cam) OR (ve cac)) duc va dinh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang x) or (nang ma)) hoi. hieu ((ve cam) OR (ve cac)) duc va dinh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang x) or (nang ma)) hoi. hieu ((ve cam) OR (ve cac)) duc va dinh vi cuu tre*.