A table or a book of tables that show the yields of bonds at differing rates of interest and maturities. As an example, if an investor is considering the purchase of a bond, then they can take the bond's coupon rate and the maturity and compare them in the bond basis book in order to determine the yield. Although the bond basis book is good for approximating the yields, in reality financial calculators are much more accurate, especially in the case of more complex bonds.