References
1. Mordell, L.J.,
Diophantine Equations
(his Chapter 30 treats the Erdös-Strauss conjecture).
2. Guy, R.,
Unsolved Problems in Number Theory
(contains over three 3 pages of Egyptian Fractions references).
3. Klee, V., and Wagon, S.,
Old and New Unsolved Problems in Plane Geometry and Number Theory
(MAA).
4. Breusch, R., A special case of Egyptian fractions, solution to advanced problem 4512, Amer. Math. Monthly, Vol 61, 1954, pp. 200201.
5. A Google search on egyptian fractions brings up a
huge
number of references (some of which I've mentioned at my web site; David Eppstein's is really superb).