I have found other site which is better than one I was telling about:
http://www.oldradioz.com/manuals/rdh4/

After going thru the Table of contents only Chapter 5 & 6 are
concerned with Transformers. Other are for Valve radios & components.
It is excellent material for those who may not have seen valves intheir
lifetime.
I suppose that there are few more sites which have design guides
for transformers and inductors using ferrite cores which will be found
in most recents equipments.