If you look up a stock, there is a standard symbol that is the same on every platform. Public Storage for example, has a symbol of PSA. But the symbols for preferred stocks are not standardized. Try to look up the series ‘L’ preferred for Public Storage, and there are several different formats.
Fortunately, Quantum Online has a handy table that shows the format probably used by your favorite stock quote site, including, Yahoo! Google Finance, Schwab and Fidelity, With examples. You can look it up here.