Perhaps you should try some spelling variations:
trinh doc » trinh do, trinh hoa, trinh co
thuc day » thuc dan, thuc vat
nang mai » nang ma, nang tai, lang mai
hieu vay » hieu va, hieu van, chieu day
vay luan » ly luan, von luan, bai luan
te sach » toc sach
cuu tre » cau tren, cau treo
thuc va » thuc vat, thuc dan
sach ty » sach y, sach tu, sach thu
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cua triet, dua tren

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 mai hoi. hieu vay luan ((thuc va) or (thuc day)) trinh doc ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang mai hoi. hieu vay luan ((thuc va) OR (thuc day)) trinh doc ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang mai hoi. hieu vay luan ((thuc va) or (thuc day)) trinh doc ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang mai hoi. hieu vay luan ((thuc va) or (thuc day)) trinh doc ((cuu tre) OR (cua tre))*.