
| R1 | A Dictionary of Science | E.B. Uvarov | 1944 |
| R2 | A Dictionary of Geography | W.G. Moore | 1949 |
| R3 | A Dictionary of Biology | M. Abercrombie et al | 1951 |
| R4 | A Dictionary of Music | Robert Illing | 1950 |
| R5 | A Dictionary of Psychology | James Drever | 1952 |
| R6 | An English-German German-English Dictionary | W.E. and J. Connell | 1954 |
| R7 | Roget's Thesaurus | Peter Mark Roget | 1953 |
| R8 | A Dictionary of Geology | G.W. Himus | 1955 |
| R9 | A Dictionary of Ballet | G.B.L. Wilson | 1957 |
| R10 | A Dictionary of Politics | Florence Elliott | 1957 |
| R11 | A Dictionary of Civil Engineering | John S. Scott | 1958 |
| R12 | A New Dictionary of Music | Arthur Jacobs | 1958 |
| R13 | The Penguin Dictionary of Architecture | John Fleming | 1966 |
| R14 | A Dictionary of Art and Artists | Peter & Linda Murray | 1959 |
| R15 | A Dictionary of Building | John S. Scott | 1964 |
| R16 | The Penguin Dictionary of Quotations | J.M. & M.J. Cohen | 1960 |
| R17 | World Events 1960 | Ivison Macadam, ed. | 1960 |
| R18 | A Dictionary of Sailing | F.H. Burgess | 1961 |
| R19 | A Dictionary of Electronics | S. Handel | 1962 |
| R20 | The Penguin Russian Course | J.L.I. Fennell | 1961 |
| R21 | The Penguin Dictionary of British Natural History | Maisie Fitter | 1967 |
| R22 | World Events 1961 | Ivison Macadam, ed. | 1961 |
| R23 | World Events 1962 | Ivison Macadam, ed. | 1962 |
| R24 | Usage and Abusage: A Guide to Good English | Eric Partridge | 1963 |
| R25 | The Penguin Book of Lieder | S.S. Prawer | 1964 |
| R26 | A Dictionary of Modern History 1789-1945 | A.W. Palmer | 1964 |
| R27 | A Shakespeare Companion 1564-1964 | F.E. Halliday | 1964 |
| R28 | A Dictionary of Astronomy | Ake Wallenquist | 1968 |
| R29 | The Penguin English Dictionary | G.N. Garmonsway | 1965 |
| R30 | A Dictionary of Saints | Donald Attwater | 1965 |
| R31 | The Penguin Encyclopedia | Sir John Summerscale | 1965 |
| R32 | A Dictionary of Surnames | Basil Cottle | 1967 |
| R33 | The Penguin Dictionary of the Theatre | John Russell Taylor | 1966 |
| R34 | The Penguin Companion to Literature 1 | David Danches, ed. | 1971 |
| R35 | The Penguin Companion to Literature 2 | Anthony Thorlby, ed. | 1969 |
| R36 | The Penguin Companion to Literature 3 | Malcolm Bradbury, ed. | 1971 |
| R37 | The Penguin Companion to Literature 4 | D.R. Dudley & D.M. Lang, eds. | 1969 |
| R38 | The Penguin Dictionary of Modern Quotations | J.M. & M.J. Cohen | 1971 |
| R39 | A Dictionary of Computers | Anthony Chandor | 1970 |
| R40 | Asia Handbook | Guy Wint, ed. | 1969 |
| R41 | Africa Handbook | Colin Legum, ed. | 1969 |
| R42 | Dictionary of American Politics | Eugene J. McCarthy | 1968 |
| R44 | The Penguin Dictionary of Commerce | Michael Greener | 1970 |
| R45 | The Penguin Dictionary of Archaeology | David Trump | 1972 |
| R46 | The Dictionary of Historical Slang | Eric Partridge | 1972 |
| R47 | The Penguin Encyclopedia of Places | W.G. Moore | 1971 |
| R48 | Penguin Medical Encyclopedia | Peter Wingate | 1972 |
| R49 | The Penguin Dictionary of Geology | J.R.V. Brooks | 1973 |