Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hoc sach » hoc sinh, hoc cac, hoc anh
tinh doi » trinh doc, trinh do, tinh hoc
su sach » so sach, vu sach
doi cua » dai cua, hoi cua
luc may » truc may, phuc may
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
ve cac » va 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) or (hoc sach)) ky nang ma hoi. hieu ((ve cac) OR (vien cac)) luc may tinh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (hoc sach)) ky nang ma hoi. hieu ((ve cac) OR (vien cac)) luc may tinh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (hoc sach)) ky nang ma hoi. hieu ((ve cac) OR (vien cac)) luc may tinh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (hoc sach)) ky nang ma hoi. hieu ((ve cac) OR (vien cac)) luc may tinh doi cua tre*.