Perhaps you should try some spelling variations:
tham thuc » nham thuc, tam thuc, thai thuc
pham thuc » phap thuc, pham chuc, nham thuc
linh kien » sinh vien, tinh dien, kinh dien
doc sach » hoc sach, toc sach, nuoc sach
dan linh » van linh, ban linh, dan minh
kien cua » khien cua, dien cua, tien cua
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
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 ky lang xa hoi. hieu va ((tham thuc) or (pham thuc)) dan linh kien cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky lang xa hoi. hieu va ((tham thuc) OR (pham thuc)) dan linh kien cua tre.
• Adding a wildcard symbol may retrieve word variants: doc sach ky lang xa hoi. hieu va ((tham thuc) or (pham thuc)) dan linh kien cua tre*.