previously mentioned Books 1 and 2 . It consists in introducing the conventional four-stage numbering , applying when necessary , a new additional four-stage numbering in the cases , when it has to be exceeded .
In the third book however , the individual sections had to be formatted independently in terms of numbering of reference literature , figures , tables and formulas due to the complexity and multifarious nature of continuous numbering . Such a problem actually arises here as with quoting text titles , although not quite often . So , except for the accepted rule for citing from one book to another , for the three books , new moments of citing appear here for quoting from one section to another in Book 3 . It is accepted to place the number of the section before the cited number of a figure , table , formula , reference literature . For example , if it is necessary to cite Fig . 56 of section 3.6 – bridges , in some other section , citing in the other section has the form ( Fig . 3.6-56 , respectively Table 3.6-5 , formula 3.6-35 , reference literature source [ 3.6-25 ]). In this way the identity is ensured .
The authors acknowledge their gratitude to the Union of Surveyors and Land Managers in Bulgaria for issuing the book under its auspices , as well as for the assistance and support rendered for the preparation and realization of the book . We also express our gratitude to the reviewers Corr . Mem . Prof . D . Sc . Dr . Arch . Atanas Kovachev and the co-reviewer Assoc . Prof . Dr . Eng . Veneta Kotseva , to Assoc . Prof . Dr . Eng . Todor Kostadinov and Dr . Eng . Ivan Kalchev Ivanov for the positive reviews of the book . We also thank Assist . Prof . Eng . Ivo Gadzhov for the cooperation in presenting digital road design , Eng . Georgi Lazarov , Eng . Yavor Dimitrov and Eng . Petar Vuchev for the effective cooperation in preparing parts for Hydrotechnical Construction , respectively to Eng . Ivailo Iliev for the gas-distribution pipelines and M . Sc . Econ . Ilian Panchev for the effective collaboration in solving problems with the computer preparation of the book . Our gratitude is also acknowledged in some sections to other colleagues with contribution to the realization of their topics .
Special thanks are due to the unreserved and active cooperation of Eng . Kristina Galabova for preparing the tables , formulas and most of the figures for press , compiling the index , etc ., as well as to Svetla Pankova and Eng . Ivanka Koleva for elaborating the title page of the book and to Eng . Ekaterina Krusteva for translating parts of the book to English .
Sofia , December , 2019 , revised 2022 The authors
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