Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
cau tren » cu tren, dau tren, ca tren
cham tuc » pham thuc, tham thuc, cham soc
tinh pho » tinh phu, tich pho, tinh cho
pho cau » pho cap, pha cau, pho cam
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa

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 ky ((nang xa) OR (lang xa)) hoi. hieu ve ((cham tuc) or (nham thuc)) may tinh pho cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (lang xa)) hoi. hieu ve ((cham tuc) OR (nham thuc)) may tinh pho cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) OR (lang xa)) hoi. hieu ve ((cham tuc) or (nham thuc)) may tinh pho cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) OR (lang xa)) hoi. hieu ve ((cham tuc) or (nham thuc)) may tinh pho cau tren*.