Hy..., as I said I Bought a collection of classic stamps..., some of them are very intriguing due to the fact that there is little or neither information related to them on the web, nor in the few catalogs I own.....I need help to identify the true value of this stamps
-20 c Volta 1927-violet..?
-15 c Caesar 1937-violet
-1929 1.75L Vitt. Em II perf 13 3/4...
-5 centessimi ,numeral inverted block o four
Thanks for your help.