Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
vien cac » vien bach, vien dai, vien da
tan hanh » tan thanh, tang hanh, toan hanh
cau tren » cu tren, dau tren, ca tren
tu sach » su sach, te sach, tu cach
va cao » va cac, va co, va dao
vi cau » va cau, ve cau, di cau
x hoi » xa hoi, o hoi, x ho

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)) ky nang x hoi. hieu ((vien cac) or (va cao)) duc tan hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang x hoi. hieu ((vien cac) OR (va cao)) duc tan hanh vi cau tren.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang x hoi. hieu ((vien cac) or (va cao)) duc tan hanh vi cau tren*.