Valence electron (English Wikipedia)

Tossell, J. A. (1 November 1977). "Theoretical studies of valence orbital binding energies in solid zinc sulfide, zinc oxide, and zinc fluoride". Inorganic Chemistry. 16 (11): 2944–2949. doi:10.1021/ic50177a056.
Chi, Chaoxian; Pan, Sudip; Jin, Jiaye; Meng, Luyan; Luo, Mingbiao; Zhao, Lili; Zhou, Mingfei; Frenking, Gernot (2019). "Octacarbonyl Ion Complexes of Actinides [An(CO)8]+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding". Chem. Eur. J. 25 (50): 11772–11784. doi:10.1002/chem.201902625. PMC 6772027. PMID 31276242.
Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 117. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
Zhou, Mingfei; Frenking, Gernot (2021). "Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba". Accounts of Chemical Research. 54 (15): 3071–3082. doi:10.1021/acs.accounts.1c00277. PMID 34264062. S2CID 235908113.
Fernández, Israel; Holzmann, Nicole; Frenking, Gernot (2020). "The Valence Orbitals of the Alkaline-Earth Atoms". Chemistry: A European Journal. 26 (62): 14194–14210. doi:10.1002/chem.202002986. PMC 7702052. PMID 32666598.

loc.gov (Global: 63^rd place; English: 47^th place)

Petrucci, Ralph H.; Harwood, William S.; Herring, F. Geoffrey (2002). General chemistry: principles and modern applications (8th ed.). Upper Saddle River, N.J: Prentice Hall. p. 339. ISBN 978-0-13-014329-7. LCCN 2001032331. OCLC 46872308.

Chi, Chaoxian; Pan, Sudip; Jin, Jiaye; Meng, Luyan; Luo, Mingbiao; Zhao, Lili; Zhou, Mingfei; Frenking, Gernot (2019). "Octacarbonyl Ion Complexes of Actinides [An(CO)8]+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding". Chem. Eur. J. 25 (50): 11772–11784. doi:10.1002/chem.201902625. PMC 6772027. PMID 31276242.
Zhou, Mingfei; Frenking, Gernot (2021). "Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba". Accounts of Chemical Research. 54 (15): 3071–3082. doi:10.1021/acs.accounts.1c00277. PMID 34264062. S2CID 235908113.
Fernández, Israel; Holzmann, Nicole; Frenking, Gernot (2020). "The Valence Orbitals of the Alkaline-Earth Atoms". Chemistry: A European Journal. 26 (62): 14194–14210. doi:10.1002/chem.202002986. PMC 7702052. PMID 32666598.

Chi, Chaoxian; Pan, Sudip; Jin, Jiaye; Meng, Luyan; Luo, Mingbiao; Zhao, Lili; Zhou, Mingfei; Frenking, Gernot (2019). "Octacarbonyl Ion Complexes of Actinides [An(CO)8]+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding". Chem. Eur. J. 25 (50): 11772–11784. doi:10.1002/chem.201902625. PMC 6772027. PMID 31276242.
Fernández, Israel; Holzmann, Nicole; Frenking, Gernot (2020). "The Valence Orbitals of the Alkaline-Earth Atoms". Chemistry: A European Journal. 26 (62): 14194–14210. doi:10.1002/chem.202002986. PMC 7702052. PMID 32666598.

Zhou, Mingfei; Frenking, Gernot (2021). "Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba". Accounts of Chemical Research. 54 (15): 3071–3082. doi:10.1021/acs.accounts.1c00277. PMID 34264062. S2CID 235908113.

Jensen, William B. (2000). "The Periodic Law and Table" (PDF). Archived from the original (PDF) on 2020-11-10. Retrieved 10 December 2022.

Jensen, William B. (2000). "The Periodic Law and Table" (PDF). Archived from the original (PDF) on 2020-11-10. Retrieved 10 December 2022.

Petrucci, Ralph H.; Harwood, William S.; Herring, F. Geoffrey (2002). General chemistry: principles and modern applications (8th ed.). Upper Saddle River, N.J: Prentice Hall. p. 339. ISBN 978-0-13-014329-7. LCCN 2001032331. OCLC 46872308.