Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
tru nang » tra nang, tri nang, truc nano
khoa hoc » hoa hoc
hieu van » hieu va, thien van, hieu ve
van hanh » van thanh, ban hanh, van anh
tu nang » tu nong, tu nano, tu lang
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
cua cau » cua cac, cua chu, cua cay
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ((tu nang) or (tru nang)) khoa hoc. ((hieu van) OR (lieu va)) cac duc van hanh vi cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((tu nang) OR (tru nang)) khoa hoc. ((hieu van) OR (lieu va)) cac duc van hanh vi cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((tu nang) or (tru nang)) khoa hoc. ((hieu van) OR (lieu va)) cac duc van hanh vi cua cau*".