Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
mai hoi » mai khoi, dai hoi, lai hoi
van bac » van ban, van bao, dan bac
van hac » van hoc, van ha, van hai
thuc va » thuc vat, thuc dan, thuc day
va xanh » va danh, va hanh, va anh
xanh di » danh di, vanh dai, xanh tai
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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 ty nang mai hoi. hieu ((van bac) or (van hac)) thuc va xanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang mai hoi. hieu ((van bac) OR (van hac)) thuc va xanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang mai hoi. hieu ((van bac) or (van hac)) thuc va xanh di cua tre*.