Perhaps you should try some spelling variations:
tham thuc » pham thuc, tam thuc, thai thuc
nham thuc » nhan thuc, nam thuc, nham thu
danh kien » dinh kien, danh viet, linh kien
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
kien cua » khien cua, dien cua, tien cua
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
va danh » va dinh, va dan, va hanh
cua tre » cua te, cuu tre, cua triet

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