SCHEMATICS and SYMBOLS : How to use them.
Schematics are like a road map for radios.   Can you imagine driving across the U.S.A. without a road map?  People who have years of experience with working on radios may be able to work on them without one, but not for long.  When driving you need to know the road signs and I am going to give you some of them for radios.

There are hundreds of thousands of schematics, and there are 3 major sources for them.   Rider started in about 1930, Samís Folders started in about 1948, and the third source was the manufacture's schematic of the radio.   Rider and the manufacture is your best bet.  Riderís first one is Roman Number I the second is II and so on.  I have from Numbers I to Numbers XIV.  I purchased all I needed from 1929 to 1942 for the old Philcoís.  Riderís Roman Number I can get very expensive, but worth it.
Now you can also get Rider on CDís but they are also very expensive.  I use only the books.  Can you imagine carrying the computer out to the workbench every time you need something or taking the chassis inside too use the computer.  Only kidding!   I just prefer taking the pages out of the books to carry around rather than printing from the CDís.
If you are using Rider, you also are going to need an index for them.  Rider is almost worthless without an index.  The index list is by the manufacture and model, NOT by the year.  This means if you have a Philco Model 95, it says 1-23, which means volume I, page 23 in the Philco section.  If you had a Philco Model 37-610, it says 7-45, that means volume VII, page 45 in the Philco section.  If you had a Philco 39-40, it says 10-19 that means volume X, page 19 in the Philco section, and so on.
The following chart shows SOME of the symbols used in schematics.