Matula 1979, стр. 1260 Matula, R. A (1979). „Electrical Resistivity of Copper, Gold, Palladium, and Silver”. Journal of Physical and Chemical Reference Data. 8 (4): 1147—298. Bibcode:1979JPCRD...8.1147M. doi:10.1063/1.555614.
Masterton & Slowinski 1977, стр. 160 list B, Si, Ge, As, Sb, and Te as metalloids, and comment that Po and At are ordinarily classified as metalloids but add that this is arbitrary as so little is known about them. Masterton, W. L; Slowinski, E. J. (1977). Chemical Principles (4th изд.). Saunders. ISBN0-7216-6173-4.. W. B. Saunders, Philadelphia,
Chang 2002, стр. 304. Chang speculates that the melting point of francium would be about 23 °C. Chang, R. (2002). Chemistry (7th изд.). ISBN0-07-246533-6.. McGraw Hill, Boston,
Rochow 1966, стр. 4 harvnb грешка: више циљева (2×): CITEREFRochow1966 (help) Rochow, E. G. (1966). The Metalloids. D.C. Health and Company.. DC Heath and Company, Boston
Davidson & Lakin 1973, стр. 627 Davidson, D. F.; Lakin, H. W (1973). „Tellurium”. Ур.: DA Brobst & WP Pratt. United States Mineral Resources. стр. 627–30. Geological survey professional paper 820, United States Government Printing Office, Washington,
Rochow 1966, стр. 41 harvnb грешка: више циљева (2×): CITEREFRochow1966 (help) Rochow, E. G. (1966). The Metalloids. D.C. Health and Company.. DC Heath and Company, Boston
Rochow 1966, стр. 224 harvnb грешка: више циљева (2×): CITEREFRochow1966 (help) Rochow, E. G. (1966). The Metalloids. D.C. Health and Company.. DC Heath and Company, Boston
Rochow 1966, стр. 7 harvnb грешка: више циљева (2×): CITEREFRochow1966 (help) Rochow, E. G. (1966). The Metalloids. D.C. Health and Company.. DC Heath and Company, Boston
Hill & Holman 2000, стр. 160. They characterise metalloids (in part) on the basis that they are "poor conductors of electricity with atomic conductance usually less than 10−3 but greater than 10−5 ohm−1 cm−4". Hill, G.; Holman, J. (2000). Chemistry in Context (5th изд.). Nelson Thornes. ISBN0-17-448307-4.. Nelson Thornes, Cheltenham,
Bond 2005, стр. 3: "One criterion for distinguishing semi-metals from true metals under normal conditions is that the bulk coordination number of the former is never greater than eight, while for metals it is usually twelve (or more, if for the body-centred cubic structure one counts next-nearest neighbours as well)." Bond, G. C (2005). Metal-Catalysed Reactions of Hydrocarbons. New York: Springer. ISBN0-387-24141-8.
Matula 1979, стр. 1260 Matula, R. A (1979). „Electrical Resistivity of Copper, Gold, Palladium, and Silver”. Journal of Physical and Chemical Reference Data. 8 (4): 1147—298. Bibcode:1979JPCRD...8.1147M. doi:10.1063/1.555614.
Greenwood 2001, стр. 2057 Greenwood, Norman N. (2001). „Main group element chemistry at the millennium”. Journal of the Chemical Society, Dalton Transactions (14): 2055—66. doi:10.1039/b103917m.
Everest 1953, стр. 4120 Everest, D. A. (1953). „838. The chemistry of bivalent germanium compounds. Part IV. Formation of germanous salts by reduction by hypophosphorous acid”. Journal of the Chemical Society: 4117—4120. doi:10.1039/JR9530004117.
Pošto je odnos zasnovan na klasičnim argumentima,[72] on ne objašnjava nalaz da polonijum, koji ima vrednost od ~0,95, usvaja metalnu (a ne kovalentnu) kristalnu strukturu, na relativističkim osnovama.[73][74] Ipak, to nudi racionalizaciju prvog reda za pojavu metalnog karaktera među elementima.[70]