Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien day » vien dai, vien da, vien xay
thuc dan » thuc hanh, thuc vat
thuc van » thuc vat, thuc va, thuc hanh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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 ty nang ma hoi. hieu vien day ((thuc van) or (((thuc dan) OR (hoc dan)))) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang ma hoi. hieu vien day ((thuc van) OR (((thuc dan) OR (hoc dan)))) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang ma hoi. hieu vien day ((thuc van) or (((thuc dan) OR (hoc dan)))) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang ma hoi. hieu vien day ((thuc van) or (((thuc dan) OR (hoc dan)))) hanh vi cua tre*.