Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, hoc sach, cuoc cach
tham thuc » nham thuc, pham thuc, tam thuc
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
tang mai » tang ma, tang tai, lang mai
cua tre » cuu tre, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu cach » tu cac
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (nuoc sach)) ky tang mai hoi. hieu van tham thuc va hanh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (nuoc sach)) ky tang mai hoi. hieu van tham thuc va hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (nuoc sach)) ky tang mai hoi. hieu van tham thuc va hanh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (nuoc sach)) ky tang mai hoi. hieu van tham thuc va hanh vi ((cua tre) OR (cua te))*.