Perhaps you should try some spelling variations:
van thuat » va thuat, van thuan, van tuan
danh dau » lanh dao, hang dau, danh tu
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
sach ky » sach y, sach ty, sach kem
thuc va » thuc dan, thuc day
dau cua » dai cua, day cua, cau cua
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sac ky)) nang ma hoi. hieu van thuat ((thuc va) OR (thuc vat)) danh dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang ma hoi. hieu van thuat ((thuc va) OR (thuc vat)) danh dau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (sac ky)) nang ma hoi. hieu van thuat ((thuc va) OR (thuc vat)) danh dau cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sac ky)) nang ma hoi. hieu van thuat ((thuc va) OR (thuc vat)) danh dau cua tre*.