Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
hanh ve » hanh vi, hanh va, hanh kem
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
ca tren » cau tren, cu tren, la tren
ty nang » ky nang, ty xang, ty hang
x hoi » o hoi, x ho, 5 hoi
ve ca » ve cac, ve cai, ve cau

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 (thu sach)) ty nang ((x hoi) or (xa hoi)). hieu van nam thuc va hanh ve ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang ((x hoi) OR (xa hoi)). hieu van nam thuc va hanh ve ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ty nang ((x hoi) or (xa hoi)). hieu van nam thuc va hanh ve ca tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ty nang ((x hoi) or (xa hoi)). hieu van nam thuc va hanh ve ca tren*.