I think the club library has books on that?
Anyway, I can tell you how I repaired my cracks. When I bought my car it had big cracks- or rather breaks in the front fender. Right from the wheel opening and working their way up. Obviously some sort of light prang had occured which had cracked a peice of glass in 2 places.
This had been patched up by somone in the past but they kept cracking. Any fiberglas patches you put underneitheth are uselss because they really only hold force in one direction, and any hit or stress is going to break through the putty over the top.
Therefor I took a knife and made the cracks bigger. Then i took my grinder and gound away a number of lines (horizontaly) accrss the crack (which was vertical) creating a series of dips. Into these dips I put a number of strands of fiberglass, This would creat a great amount of strength. The wider cracks helped more resin get into all the places.
Then I put fiberglas patches on back which wouldnt be seen by anyone anyway. I tell u what, it doesnt look pretty but after it dried I gave it a good sanding. THEN the putty went on, and the rest is history.
the hardest bit was puttin the grinder to the body work- its all mental. But I can tell you i can grab onto the fender and try to pick the car up and the crack wont reapear.
Adam