Johnson, L A M; Gill, P; Margolis, H S (2015) Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10 -21 level. Metrologia, 52 (1). pp. 62-71.

Barwood, G P; Huang, G; Klein, H A; Johnson, L A M; King, S A; Margolis, H S; Szymaniec, K; Gill, P (2014) Agreement between two 88Sr+ optical clocks to 4 parts in 10^17. Phys. Rev. A, 89 (5). 050501

Godun, R M; Nisbet-Jones, P B R; Jones, J M; King, S A; Johnson, L A M; Margolis, H S; Szymaniec, K; Lea, S N; Bongs, K*; Gill, P (2014) Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time-variation of fundamental constants. Phys. Rev. Lett., 113 (21). 210801

Parker, B; Marra, G; Johnson, L A M; Margolis, H S; Webster, S A; Wright, L; Lea, S N; Gill, P; Bayvel, P* (2014) Transportable cavity-stabilised laser system for optical carrier frequency transmission experiments. Appl. Opt., 53 (35). pp. 8157-8166.

King, S A; Godun, R M; Webster, S A; Margolis, H S; Johnson, L A M; Szymaniec, K; Baird, P E G*; Gill, P (2012) Absolute frequency measurement of the 2S- 1/2 - 2F-2 7/2) electric octupole transition in a single ion of Yb-171(+) with 10(-15) fractional uncertainty. New J. Phys., 14 (1). 013045