Perhaps you should try some spelling variations:
thuoc sach » nuoc sach, thuat sach, thuoc sinh
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
hoc sach » hoc sinh, hoc cac, hoc anh
duc van » duc va, duc tan, duc manh
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
ma hoi » mai hoi, xa hoi, ma hoa
ve cam » ve cham, va cam, ve cai
ve cac » va cac, vien cac
vai va » mai va, dai va, hai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (ve cac)) duc van thanh vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) OR (ve cac)) duc van thanh vai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (ve cac)) duc van thanh vai va thiet".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) OR (hoc sach)) ky tang ma hoi. hieu ((ve cam) or (ve cac)) duc van thanh vai va thiet*.