i want to learn about transformer .If you would like to tell us what sort of transformers you are talking about, perhaps we can be more specific.
Do you mean mains transformers, signal transformers, current or instrument transformers, powere converter transformers including switching regulators. welding transformers or what?
Also what sort of information you seek.
Bernards Radio Manual no 160 Coil Design and Construction tells you all about the practicalities of making power transformers for electronic equiment, interstage tranformers for electronic circuits, but is purely practical, and does not explain any theory.
V Capel's PA systems will tell you all about audio line transformers and their use in public address systems.
Shure applications notes will tell you about microphone transformers
So over to you for more information about your needs.