Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
chat duc » chat xuc, chat doc, chet duoc
hieu ve » hieu va, hieu van
ve chat » va chat, van chat
duc van » duc va, duc tan, duc manh
nang ma » tang ma, sang ma, nang cao
tu sach » thu sach, su sach, te sach

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 y ((nang ma) or (nang x)) hoi. hieu ve chat duc van hanh tai ((cua triet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (nang x)) hoi. hieu ve chat duc van hanh tai ((cua triet) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (nang x)) hoi. hieu ve chat duc van hanh tai ((cua triet) or (va triet))*.