SIGN, SYMBOL, AND SCRIPT
This is a major work of reference and while other newer works have replaced and supplemtned this if you either get a chance ot read it or acquire it here's why you should.
The edition I have acess to via a library is the 3rd edition 1969 which is also the first English edition translated from German.
Photos Yes the photos are black and white but I've seen worse on the web.
Diagrams Lots and lots of charts of letters and their equivalent sounds in English.
You may recognize many of them being ripped off in later works.
Certain scholars amateur and academic apparently can't be bothered to update the charts and diagrams or improve them or modernize them by adding IPA values.
One of the later standard reference works is undoubtedly Daneil Bright's book and he updates in areas where new discoveries have been made later but there are some sections in which Jensen goes more detail than Bright.
If you see Jensen's book do read it and photocopy or scan some pages within legal limits.
Just in case your library's copy becomes a victim of the duh this is old and it only gets read once a year so people can just go read it on google books so we have more shelf space mentality?
Jensen Sign, Symbol, and Script. Keep a eye out for it!