Perhaps you should try some spelling variations:
thach thuc » thuc thuc, thanh thuy, cach thuc
danh dien » dinh dien, danh kien, danh lien
hac thuc » hoc thuc, ha thuc, thuc thuc
dien cuu » dien cuc, dien cu, dien cua
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
va danh » va dinh, va dan, va hanh
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cuu tre » cua tre, cau tren, cau treo

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

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