Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
thu sach » tu sach, thuat sach, thuoc sach
dua tren » dung tren
ty hang » ly hang, ty xang, thi hang
mai hoi » mai khoi, dai hoi, lai hoi
luc van » luoc van, luu van, duc van
ty lang » tay lang, ty xang, tu lang
vai dua » dai dua, vai cua
ve cac » va cac, vien cac
ve cau » ke cau, va cau, le cau

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 ((ty lang) or (ty hang)) mai hoi. hieu ((ve cau) or (ve cac)) luc van thanh vai dua tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ty lang) OR (ty hang)) mai hoi. hieu ((ve cau) OR (ve cac)) luc van thanh vai dua tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ((ty lang) or (ty hang)) mai hoi. hieu ((ve cau) or (ve cac)) luc van thanh vai dua tren*.