Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
viet cua » viec cua, viet ca, viet qua
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
viet ha » viet nam
ma hoi » mai hoi, xa hoi, ma hoa

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 ky nang ma hoi. hieu van tham thuc va danh ((viet cua) or (viet ha)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang ma hoi. hieu van tham thuc va danh ((viet cua) OR (viet ha)) tre.
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang ma hoi. hieu van tham thuc va danh ((viet cua) or (viet ha)) tre*.