I've been thinking about a problem i.e. Stability of cyclopropenyl cation vs tropylium cation.

According to Huckel's molecular orbital theory their resonance energies are 2β and 3β respectively. Obviously tropylium cation has more resonance energy but for resonance stabilization I think it is more convenient to take ENERGY DISTRIBUTION PER ATOM for consideration. Further more the energy contribution per atom, more will be the extent of overlapping hence more will be the stability provided for e.g. Benzene & Naphthalene we talk about the energy contribution per atom for resonance (resonance energy per benzene ring). As a result, we say Benzene is more stable.

I've been taught that cyclopropenyl cation forms exceptionally stable banana bonds with perfect overlapping of the p-orbitals. If overlapping in so good than the value of RESONANCE INTEGRAL increases. Although we take it constant as - 75kcal/mole but its value varies with extent of overlapping.

The C-C bond length of cyclopropenyl cation is about 138pm while it is 147pm in tropylium and 140pm in Benzene. It is shorter in cyclopropenyl cation meaning overlapping been too good there. I'm taking bond lengths in account because as the bond length increases the molecule start gaining NON-AROMATIC CHARACTER. It means cyclopropenyl cation is more planer than tropylium one.

I want to study about the exceptional bonding behaviour of the cyclopropenyl cation. I need good research articles or reference book for the same. Is anyone there to help me?