1936 (February 28), ''Air Mail. Six Cents'' surcharges, complete set of three on local FD cover with appropriate Monrovia date stamp, usual soiling, still F/VF and scarce, C.v. $825 as for set off cover, Est. $300-$400 (Image)

1937-45, Waco Plane, 1c-6c, perforated and imperforated complete sets of six in tete-beche pairs, five pairs imperforated between (E. Kessler guarantees) and four stamps with later surcharges (one - inverted), in addition three Air Mail covers of 1937 from Monrovia to Germany, Austria or Gold Coast, stamps with full OG, NH or LH (surcharges, one - used), all are VF, C.v. $557 for stamps only, Est. $300-$400 (Image)

1892, Hippopotamus, perforated essay of $1 in yellow brown and black, miniature sheet of ten stamps, each one overprinted ''Waterlow & Sons Ltd. Specimen'', security punch at the bottom left corner, no gum as produced, VF and scarce item, especially in complete pane, Est. $400-$500 (Image)

1892, Liberian Star, perforated proof of $2 in green, miniature sheet of ten stamps, each one overprinted ''Waterlow & Sons Ltd. Specimen'' with security punch at the bottom left corner, minor perf separation at bottom margin only, no gum as produced, VF, Est. $300-$400 (Image)

Air Post stamps. 1938, Airplanes and Birds, imperforated plate proofs of 1c-$1, set of ten in pairs, each stamp with ''Proof'' overprint in black, less 20c (not issued in such format), but including two of 4c in orange (issued color) and yellow, perfect condition, full OG, NH, VF and very scarce, Est. $400-$500 (Image)