Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cham thuc » nham thuc, pham thuc, tham thuc
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
hieu ve » hieu va, hieu van
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
ve cham » va cham, ve chat, vu cham
vi su » va su, ve su, oi su
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thuoc sach)) ky lang xa hoi. hieu ve cham thuc dan hanh ((vi su) OR (ki su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky lang xa hoi. hieu ve cham thuc dan hanh ((vi su) OR (ki su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) ky lang xa hoi. hieu ve cham thuc dan hanh ((vi su) OR (ki su)) triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky lang xa hoi. hieu ve cham thuc dan hanh ((vi su) OR (ki su)) triet*.