Herzberg, Philipp Yorck; Glaesmer, Heide; Hoyer, Jürgen (2006). "Separating optimism and pessimism: A robust psychometric analysis of the Revised Life Orientation Test (LOT-R)". Psychological Assessment. 18 (4): 433–438. doi:10.1037/1040-3590.18.4.433. PMID17154764. S2CID14674536.
Herzberg, Philipp Yorck; Glaesmer, Heide; Hoyer, Jürgen (2006). "Separating optimism and pessimism: A robust psychometric analysis of the Revised Life Orientation Test (LOT-R)". Psychological Assessment. 18 (4): 433–438. doi:10.1037/1040-3590.18.4.433. PMID17154764. S2CID14674536.
Herzberg, Philipp Yorck; Glaesmer, Heide; Hoyer, Jürgen (2006). "Separating optimism and pessimism: A robust psychometric analysis of the Revised Life Orientation Test (LOT-R)". Psychological Assessment. 18 (4): 433–438. doi:10.1037/1040-3590.18.4.433. PMID17154764. S2CID14674536.