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
lang mai » lang dai, lang hai, sang mai
lang man » lang van, lang ban, dang manh
luc van » luoc van, luu van, duc van
sach ky » sac ky, sach y, sach ty
va tren » va trien, van tren, va tre
ve cac » vien cac
vai va » mai va, dai va, hai va

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