Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
nam thuc » nam thuoc, am thuc, nam thu
hanh dao » lanh dao, thanh dat, thanh dam
hieu van » hieu va, thien van, lieu va
dao cua » dai cua, day cua, dan cua
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, dam thuc
lang xa » lang ha, dang xay, lang van
ty lang » tay lang, ty xang, ty hang
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: ((thu sach) or (thuoc sach)) ty lang xa hoi. hieu van ((cam tuc) OR (nam thuc)) va hanh dao cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ty lang xa hoi. hieu van ((cam tuc) OR (nam thuc)) va hanh dao cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuoc sach)) ty lang xa hoi. hieu van ((cam tuc) OR (nam thuc)) va hanh dao cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) ty lang xa hoi. hieu van ((cam tuc) OR (nam thuc)) va hanh dao cua tre*.