Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
vat hanh » vat thanh, van hanh, va hanh
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky lang xa hoi. hieu van cham thuc vat hanh vi ((cua tre) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky lang xa hoi. hieu van cham thuc vat hanh vi ((cua tre) OR (cua tu)).
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky lang xa hoi. hieu van cham thuc vat hanh vi ((cua tre) or (cua tu))*.