Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thanh vai » thanh hai, thanh van, thanh oai
thu sach » tu sach, thuat sach, thuoc sach
dua tren » dung tren
sang tao » hang tai
sach ky » sac ky, sach y, sach ty
luu van » cuu van, luan van, luu hanh
tao hoi » tao khoi, tao boi, tay hoi
ky sang » ky nang, ky dang, ky tang
ve cau » ke cau, va cau, le cau
ve cac » va cac, vien cac

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 ky sang tao hoi. hieu ((ve cau) or (ve cac)) luu van ((thanh vai) OR (thanh tai)) dua tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky sang tao hoi. hieu ((ve cau) OR (ve cac)) luu van ((thanh vai) OR (thanh tai)) dua tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky sang tao hoi. hieu ((ve cau) or (ve cac)) luu van ((thanh vai) OR (thanh tai)) dua tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ky sang tao hoi. hieu ((ve cau) or (ve cac)) luu van ((thanh vai) OR (thanh tai)) dua tren*.