Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
viet cua » viec cua, viet ca, viet qua
te sach » toc sach
va kinh » va tinh, qua kinh
va ninh » van ninh, va tinh, va sinh
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
ve cac » va cac
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang ma hoi. hieu ((ve cac) or (vien cac)) day ((va ninh) OR (va kinh)) viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang ma hoi. hieu ((ve cac) OR (vien cac)) day ((va ninh) OR (va kinh)) viet cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang ma hoi. hieu ((ve cac) or (vien cac)) day ((va ninh) OR (va kinh)) viet cua tre*".