Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
dau tren » dau tien, dat tren, dau tieng
lang mai » lang dai, lang hai, lang man
mai khoi » mai khoa, tai khoa, cac khoi
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
cham duc » pham duc, cham soc, pham duy
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
ca tren » cau tren, cu tren, la tren

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 ky lang mai khoi. hieu van cham duc va hanh tai ((cuu tre) or (((dau tren) or (ca tren))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang mai khoi. hieu van cham duc va hanh tai ((cuu tre) OR (((dau tren) OR (ca tren)))).
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang mai khoi. hieu van cham duc va hanh tai ((cuu tre) or (((dau tren) or (ca tren))))*.