▁Ned el cho ▁Mark ov ▁E ne v , ▁S vet la ▁Gen ova ▁Rak ad z hi y ska , ▁Mar in ▁Na iden ov ▁N esh kov , ▁Bel che va ▁Tat iana ▁H rist ova , ▁Kos io ▁Y ord an ov ▁Kost adin ov , ▁T anya ▁D abe va ▁Philipp ova ) ▁Econom ics ▁and ▁Organ ization ▁of ▁Tour ism ▁( text book ▁for ▁students ▁of ▁spec . ▁International ▁tour ism ▁at ▁V IN S ▁B lag o ev ▁– ▁V arna ). ▁V arna : ▁G . B ak al ov , ▁ 1 9 8 7 , ▁ 2 4 8 p . ▁ ▁Tra vel ▁Resources . ▁V arna , ▁University ▁Press ▁И У , ▁ 2 0 0 3 , ▁p . 3 8 8 . ▁▁ ▁( co - author ed ▁with ▁Georg i ▁Georg iev ▁Ch ank ov ) ▁Tra vel ▁Resources . ▁B lag o ev grad , ▁University ▁Press ▁Ne of it ▁Bo z vel i , ▁ 2 0 0 6 , ▁ 5 8 3 p . ▁ ▁( co - author ed ▁with ▁Ivan ▁Mark ov ) ▁Tra vel ▁Resources . ▁Vel iko ▁T yr n ovo , ▁A ST AR TA , ▁ 2 0 0 8 , ▁ 4 7 9 ▁p . ▁ ▁Articles ▁ ▁Naj den ▁Apost ol ov , ▁Un ut ar grad ska ▁sa ob ra ċ aj na ▁dost up nost ▁grad ova ▁bug ars ke ▁, ▁Ge ographical ▁Institute