Perhaps you should try some spelling variations:
ve triet » va trien, su triet
hanh dai » hanh tai, hanh dao, vanh dai
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ca viet » va viet, co viet, hoa viet
hieu ve » hieu va, hieu van
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa
ve am » va am

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hai)). hieu ve am thuc dan hanh dai ((ve triet) OR (ca viet))~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (o hai)). hieu ve am thuc dan hanh dai ((ve triet) or (ca viet))*.