Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
sach hoa » sach ha, sach hoi, bach hoa
hoa nang » hoa lang, ho nang, hoi nang
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hanh de » hanh ve, hanh kem
hang vi » hang va, hanh vi, hang di
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
va nam » van nam, ha nam, va nay
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 hoa nang ((x hoi) or (o hoi)). hieu va nam thuc dan ((hang vi) or (hanh de)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoa nang ((x hoi) OR (o hoi)). hieu va nam thuc dan ((hang vi) OR (hanh de)) va triet.
• Adding a wildcard symbol may retrieve word variants: tu sach hoa nang ((x hoi) or (o hoi)). hieu va nam thuc dan ((hang vi) or (hanh de)) va triet*.